diff --git a/.github/workflows/crashlytics.yml b/.github/workflows/crashlytics.yml
index 5638d5d35bc..f24d0f63de5 100644
--- a/.github/workflows/crashlytics.yml
+++ b/.github/workflows/crashlytics.yml
@@ -25,20 +25,23 @@ jobs:
     strategy:
       matrix:
         target: [ios, tvos, macos, watchos --skip-tests]
-        os: [macos-14]
         flags: [
           '--use-modular-headers --skip-tests',
           ''
         ]
-        xcode: [Xcode_15.2, Xcode_16]
-    runs-on: ${{ matrix.os }}
+        build-env:
+          - os: macos-14
+            xcode: Xcode_15.2
+          - os: macos-15
+            xcode: Xcode_16.1
+    runs-on: ${{ matrix.build-env.os }}
     steps:
     - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@v1
     - name: Setup Bundler
       run: scripts/setup_bundler.sh
     - name: Xcode
-      run: sudo xcode-select -s /Applications/${{ matrix.xcode }}.app/Contents/Developer
+      run: sudo xcode-select -s /Applications/${{ matrix.build-env.xcode }}.app/Contents/Developer
     - uses: nick-fields/retry@v3
       with:
         timeout_minutes: 120
@@ -85,22 +88,22 @@ jobs:
             xcode: Xcode_15.4
             target: iOS
           - os: macos-15
-            xcode: Xcode_16
+            xcode: Xcode_16.1
             target: iOS
           - os: macos-15
-            xcode: Xcode_16
+            xcode: Xcode_16.1
             target: tvOS
           - os: macos-15
-            xcode: Xcode_16
+            xcode: Xcode_16.1
             target: macOS
           - os: macos-15
-            xcode: Xcode_16
+            xcode: Xcode_16.1
             target: watchOS
           - os: macos-15
-            xcode: Xcode_16
+            xcode: Xcode_16.1
             target: catalyst
           - os: macos-15
-            xcode: Xcode_16
+            xcode: Xcode_16.1
             target: visionOS
     runs-on: ${{ matrix.os }}
     steps:
@@ -149,7 +152,7 @@ jobs:
     env:
       plist_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
       signin_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
-    runs-on: macos-14
+    runs-on: macos-15
     steps:
     - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@v1
diff --git a/.github/workflows/dynamiclinks.yml b/.github/workflows/dynamiclinks.yml
index 61439d6cc3c..9304532dc90 100644
--- a/.github/workflows/dynamiclinks.yml
+++ b/.github/workflows/dynamiclinks.yml
@@ -114,7 +114,7 @@ jobs:
     env:
       plist_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
       signin_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
-    runs-on: macos-14
+    runs-on: macos-15
     steps:
     - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@v1
diff --git a/.github/workflows/inappmessaging.yml b/.github/workflows/inappmessaging.yml
index c8d70fbeff4..9464fa3a245 100644
--- a/.github/workflows/inappmessaging.yml
+++ b/.github/workflows/inappmessaging.yml
@@ -24,14 +24,17 @@ jobs:
     strategy:
       matrix:
         podspec: [FirebaseInAppMessaging.podspec]
-        os: [macos-14]
-        xcode: [Xcode_15.2, Xcode_16]
-    runs-on: ${{ matrix.os }}
+        build-env:
+          - os: macos-14
+            xcode: Xcode_15.2
+          - os: macos-15
+            xcode: Xcode_16.1
+    runs-on: ${{ matrix.build-env.os }}
     steps:
     - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@v1
     - name: Xcode
-      run: sudo xcode-select -s /Applications/${{ matrix.xcode }}.app/Contents/Developer
+      run: sudo xcode-select -s /Applications/${{ matrix.build-env.xcode }}.app/Contents/Developer
     - name: Setup Bundler
       run: scripts/setup_bundler.sh
     - name: FirebaseInAppMessaging
@@ -97,7 +100,7 @@ jobs:
           - os: macos-14
             xcode: Xcode_15.4
           - os: macos-15
-            xcode: Xcode_16
+            xcode: Xcode_16.1
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v4
@@ -139,7 +142,7 @@ jobs:
     env:
       plist_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
       signin_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
-    runs-on: macos-14
+    runs-on: macos-15
 
     steps:
     - uses: actions/checkout@v4
diff --git a/.github/workflows/installations.yml b/.github/workflows/installations.yml
index 3a1da8aa802..d0913c2ed19 100644
--- a/.github/workflows/installations.yml
+++ b/.github/workflows/installations.yml
@@ -25,15 +25,14 @@ jobs:
       matrix:
         # TODO: macos tests are blocked by https://github.com/erikdoe/ocmock/pull/532
         target: [ios, tvos, macos --skip-tests, watchos]
-        os: [macos-14]
-        include:
+        build-env:
           - os: macos-14
-            xcode: Xcode_15.3
+            xcode: Xcode_15.2
             test-specs: unit,integration
-          - os: macos-14
-            xcode: Xcode_16
+          - os: macos-15
+            xcode: Xcode_16.1
             test-specs: unit
-    runs-on: ${{ matrix.os }}
+    runs-on: ${{ matrix.build-env.os }}
     steps:
     - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@v1
@@ -50,12 +49,12 @@ jobs:
       id: secrets
       run: echo "::set-output name=val::$([[ -z $plist_secret ]] && echo "0" || echo "1")"
     - name: Xcode
-      run: sudo xcode-select -s /Applications/${{ matrix.xcode }}.app/Contents/Developer
+      run: sudo xcode-select -s /Applications/${{ matrix.build-env.xcode }}.app/Contents/Developer
     - name: Build and test
       run: |
        export FIS_INTEGRATION_TESTS_REQUIRED=${{ steps.secrets.outputs.val }}
        scripts/third_party/travis/retry.sh scripts/pod_lib_lint.rb FirebaseInstallations.podspec \
-         --platforms=${{ matrix.target }} --test-specs=${{ matrix.test-specs }}
+         --platforms=${{ matrix.target }} --test-specs=${{ matrix.build-env.test-specs }}
 
   spm-package-resolved:
     env:
@@ -93,22 +92,22 @@ jobs:
             xcode: Xcode_15.4
             target: iOS
           - os: macos-15
-            xcode: Xcode_16
+            xcode: Xcode_16.1
             target: iOS
           - os: macos-15
-            xcode: Xcode_16
+            xcode: Xcode_16.1
             target: tvOS
           - os: macos-15
-            xcode: Xcode_16
+            xcode: Xcode_16.1
             target: macOS
           - os: macos-15
-            xcode: Xcode_16
+            xcode: Xcode_16.1
             target: watchOS
           - os: macos-15
-            xcode: Xcode_16
+            xcode: Xcode_16.1
             target: catalyst
           - os: macos-15
-            xcode: Xcode_16
+            xcode: Xcode_16.1
             target: visionOS
     runs-on: ${{ matrix.os }}
     steps:
diff --git a/.github/workflows/remoteconfig.yml b/.github/workflows/remoteconfig.yml
index eb5cae871c7..2036d8ab274 100644
--- a/.github/workflows/remoteconfig.yml
+++ b/.github/workflows/remoteconfig.yml
@@ -62,28 +62,27 @@ jobs:
         # TODO: macos tests are blocked by https://github.com/erikdoe/ocmock/pull/532
         target: [ios, tvos, macos --skip-tests, watchos]
         podspec: [FirebaseRemoteConfig.podspec]
-        os: [macos-14]
-        include:
+        build-env:
           - os: macos-14
             xcode: Xcode_15.3
             # TODO(#13078): Fix testing infra to enforce warnings again.
             tests: --allow-warnings
           # Flaky tests on CI
-          - os: macos-14
-            xcode: Xcode_16
+          - os: macos-15
+            xcode: Xcode_16.1
             tests: --skip-tests
-    runs-on: ${{ matrix.os }}
+    runs-on: ${{ matrix.build-env.os }}
     steps:
     - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@v1
     - name: Setup Bundler
       run: scripts/setup_bundler.sh
     - name: Xcode
-      run: sudo xcode-select -s /Applications/${{ matrix.xcode }}.app/Contents/Developer
+      run: sudo xcode-select -s /Applications/${{ matrix.build-env.xcode }}.app/Contents/Developer
     - name: Build and test
       run: |
        scripts/third_party/travis/retry.sh scripts/pod_lib_lint.rb ${{ matrix.podspec }} --platforms=${{ matrix.target }} \
-         ${{ matrix.tests }}
+         ${{ matrix.build-env.tests }}
 
   spm-package-resolved:
     env:
@@ -124,27 +123,27 @@ jobs:
             target: iOS
             test: spm
           - os: macos-15
-            xcode: Xcode_16
+            xcode: Xcode_16.1
             target: iOS
             test: spm
           - os: macos-15
-            xcode: Xcode_16
+            xcode: Xcode_16.1
             target: tvOS
             test: spm
           - os: macos-15
-            xcode: Xcode_16
+            xcode: Xcode_16.1
             target: macOS
             test: spm
           - os: macos-15
-            xcode: Xcode_16
+            xcode: Xcode_16.1
             target: watchOS
             test: spmbuildonly
           - os: macos-15
-            xcode: Xcode_16
+            xcode: Xcode_16.1
             target: catalyst
             test: spm
           - os: macos-15
-            xcode: Xcode_16
+            xcode: Xcode_16.1
             target: visionOS
             test: spm
     runs-on: ${{ matrix.os }}
@@ -184,7 +183,7 @@ jobs:
     env:
       plist_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
       signin_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
-    runs-on: macos-14
+    runs-on: macos-15
     steps:
     - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@v1
diff --git a/.github/workflows/sessions.yml b/.github/workflows/sessions.yml
index 73fff13c7aa..cddd363aebe 100644
--- a/.github/workflows/sessions.yml
+++ b/.github/workflows/sessions.yml
@@ -24,30 +24,29 @@ jobs:
     strategy:
       matrix:
         target: [ios, tvos, macos, watchos]
-        os: [macos-14]
-        include:
+        build-env:
           - os: macos-14
             xcode: Xcode_15.3
             tests:
           # Flaky tests on CI
-          - os: macos-14
-            xcode: Xcode_16
+          - os: macos-15
+            xcode: Xcode_16.1
             tests: --skip-tests
-    runs-on: ${{ matrix.os }}
+    runs-on: ${{ matrix.build-env.os }}
     steps:
     - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@v1
     - name: Setup Bundler
       run: scripts/setup_bundler.sh
     - name: Xcode
-      run: sudo xcode-select -s /Applications/${{ matrix.xcode }}.app/Contents/Developer
+      run: sudo xcode-select -s /Applications/${{ matrix.build-env.xcode }}.app/Contents/Developer
     - uses: nick-fields/retry@v3
       with:
         timeout_minutes: 120
         max_attempts: 3
         retry_on: error
         retry_wait_seconds: 120
-        command: scripts/third_party/travis/retry.sh scripts/pod_lib_lint.rb FirebaseSessions.podspec --platforms=${{ matrix.target }} ${{ matrix.tests }}
+        command: scripts/third_party/travis/retry.sh scripts/pod_lib_lint.rb FirebaseSessions.podspec --platforms=${{ matrix.target }} ${{ matrix.build-env.tests }}
 
   spm-package-resolved:
     env:
@@ -86,22 +85,22 @@ jobs:
             xcode: Xcode_15.4
             target: iOS
           - os: macos-15
-            xcode: Xcode_16
+            xcode: Xcode_16.1
             target: iOS
           - os: macos-15
-            xcode: Xcode_16
+            xcode: Xcode_16.1
             target: tvOS
           - os: macos-15
-            xcode: Xcode_16
+            xcode: Xcode_16.1
             target: macOS
           - os: macos-15
-            xcode: Xcode_16
+            xcode: Xcode_16.1
             target: watchOS
           - os: macos-15
-            xcode: Xcode_16
+            xcode: Xcode_16.1
             target: catalyst
           - os: macos-15
-            xcode: Xcode_16
+            xcode: Xcode_16.1
             target: visionOS
     runs-on: ${{ matrix.os }}
     steps:
diff --git a/.github/workflows/storage.yml b/.github/workflows/storage.yml
index 220f98b5741..790e8ebd39d 100644
--- a/.github/workflows/storage.yml
+++ b/.github/workflows/storage.yml
@@ -139,8 +139,8 @@ jobs:
           #- os: macos-13
           #  xcode: Xcode_14.2 # TODO: the legacy ObjC quickstart doesn't build with Xcode 15.
           - swift: swift
-            os: macos-14
-            xcode: Xcode_15.3
+            os: macos-15
+            xcode: Xcode_16.1
     env:
       plist_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
       signin_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
diff --git a/.github/workflows/zip.yml b/.github/workflows/zip.yml
index 2dd23dcc7fd..2db3f9d86be 100644
--- a/.github/workflows/zip.yml
+++ b/.github/workflows/zip.yml
@@ -30,7 +30,7 @@ jobs:
   package-release:
     # Don't run on private repo.
     if: (github.repository == 'Firebase/firebase-ios-sdk' && github.event_name == 'schedule') || github.event_name == 'pull_request' || github.event_name == 'workflow_dispatch'
-    runs-on: macos-13
+    runs-on: macos-14
     steps:
     - uses: actions/checkout@v4
     - uses: mikehardy/buildcache-action@c87cea0ccd718971d6cc39e672c4f26815b6c126
@@ -58,7 +58,7 @@ jobs:
   build:
     # Don't run on private repo unless it is a PR.
     if: (github.repository == 'Firebase/firebase-ios-sdk' && github.event_name == 'schedule') || github.event_name == 'pull_request' || github.event_name == 'workflow_dispatch'
-    runs-on: macos-13
+    runs-on: macos-14
     steps:
     - uses: actions/checkout@v4
     - name: Xcode 15.2
@@ -75,7 +75,7 @@ jobs:
     strategy:
       matrix:
         linking_type: [static, dynamic]
-    runs-on: macos-13
+    runs-on: macos-14
     steps:
     - uses: actions/checkout@v4
     - uses: mikehardy/buildcache-action@c87cea0ccd718971d6cc39e672c4f26815b6c126
@@ -111,14 +111,13 @@ jobs:
       SDK: "ABTesting"
     strategy:
       matrix:
-        os: [macos-13, macos-14]
         artifact: [Firebase-actions-dir, Firebase-actions-dir-dynamic]
-        include:
-          - os: macos-13
-            xcode: Xcode_15.2
+        build-env:
           - os: macos-14
-            xcode: Xcode_16
-    runs-on: ${{ matrix.os }}
+            xcode: Xcode_15.2
+          - os: macos-15
+            xcode: Xcode_16.1
+    runs-on: ${{ matrix.build-env.os }}
     steps:
     - uses: actions/checkout@v4
     - name: Get framework dir
@@ -134,7 +133,7 @@ jobs:
         find "${GITHUB_WORKSPACE}" -name "Firebase*latest.zip" -exec unzip -d "${HOME}"/ios_frameworks/ {} +
     - uses: actions/checkout@v4
     - name: Xcode
-      run: sudo xcode-select -s /Applications/${{ matrix.xcode }}.app/Contents/Developer
+      run: sudo xcode-select -s /Applications/${{ matrix.build-env.xcode }}.app/Contents/Developer
     - name: Setup quickstart
       env:
         LEGACY: true
@@ -173,11 +172,11 @@ jobs:
       SDK:  "Authentication"
     strategy:
       matrix:
-        os: [macos-14]
+        os: [macos-15]
         artifact: [Firebase-actions-dir, Firebase-actions-dir-dynamic]
         include:
-          - os: macos-14
-            xcode: Xcode_16
+          - os: macos-15
+            xcode: Xcode_16.1
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v4
@@ -225,14 +224,13 @@ jobs:
       SDK: "Config"
     strategy:
       matrix:
-        os: [macos-13, macos-14]
         artifact: [Firebase-actions-dir, Firebase-actions-dir-dynamic]
-        include:
-          - os: macos-13
-            xcode: Xcode_15.2
+        build-env:
           - os: macos-14
-            xcode: Xcode_16
-    runs-on: ${{ matrix.os }}
+            xcode: Xcode_15.2
+          - os: macos-15
+            xcode: Xcode_16.1
+    runs-on: ${{ matrix.build-env.os }}
     steps:
     - uses: actions/checkout@v4
     - name: Get framework dir
@@ -247,7 +245,7 @@ jobs:
         mkdir -p "${HOME}"/ios_frameworks/
         find "${GITHUB_WORKSPACE}" -name "Firebase*latest.zip" -exec unzip -d "${HOME}"/ios_frameworks/ {} +
     - name: Xcode
-      run: sudo xcode-select -s /Applications/${{ matrix.xcode }}.app/Contents/Developer
+      run: sudo xcode-select -s /Applications/${{ matrix.build-env.xcode }}.app/Contents/Developer
     - name: Setup Swift Quickstart
 
       run: SAMPLE="$SDK" TARGET="${SDK}Example" scripts/setup_quickstart_framework.sh \
@@ -277,14 +275,13 @@ jobs:
       SDK: "Crashlytics"
     strategy:
       matrix:
-        os: [macos-13, macos-14]
         artifact: [Firebase-actions-dir, Firebase-actions-dir-dynamic]
-        include:
-          - os: macos-13
-            xcode: Xcode_15.2
+        build-env:
           - os: macos-14
-            xcode: Xcode_16
-    runs-on: ${{ matrix.os }}
+            xcode: Xcode_15.2
+          - os: macos-15
+            xcode: Xcode_16.1
+    runs-on: ${{ matrix.build-env.os }}
     steps:
     - uses: actions/checkout@v4
     - name: Get framework dir
@@ -300,7 +297,7 @@ jobs:
         find "${GITHUB_WORKSPACE}" -name "Firebase*latest.zip" -exec unzip -d "${HOME}"/ios_frameworks/ {} +
     - uses: actions/checkout@v4
     - name: Xcode
-      run: sudo xcode-select -s /Applications/${{ matrix.xcode }}.app/Contents/Developer
+      run: sudo xcode-select -s /Applications/${{ matrix.build-env.xcode }}.app/Contents/Developer
     - name: Setup quickstart
       env:
         LEGACY: true
@@ -352,7 +349,7 @@ jobs:
       SDK: "Database"
     strategy:
       matrix:
-        os: [macos-13]
+        os: [macos-14]
         xcode: [Xcode_15.2]
         artifact: [Firebase-actions-dir, Firebase-actions-dir-dynamic]
     runs-on: ${{ matrix.os }}
@@ -404,14 +401,13 @@ jobs:
       SDK: "DynamicLinks"
     strategy:
       matrix:
-        os: [macos-13, macos-14]
         artifact: [Firebase-actions-dir, Firebase-actions-dir-dynamic]
-        include:
-          - os: macos-13
-            xcode: Xcode_15.2
+        build-env:
           - os: macos-14
-            xcode: Xcode_16
-    runs-on: ${{ matrix.os }}
+            xcode: Xcode_15.2
+          - os: macos-15
+            xcode: Xcode_16.1
+    runs-on: ${{ matrix.build-env.os }}
     steps:
     - uses: actions/checkout@v4
     - name: Get framework dir
@@ -430,7 +426,7 @@ jobs:
                                                "${HOME}"/ios_frameworks/Firebase/FirebaseDynamicLinks/* \
                                                "${HOME}"/ios_frameworks/Firebase/FirebaseAnalytics/*
     - name: Xcode
-      run: sudo xcode-select -s /Applications/${{ matrix.xcode }}.app/Contents/Developer
+      run: sudo xcode-select -s /Applications/${{ matrix.build-env.xcode }}.app/Contents/Developer
     - name: Setup Swift Quickstart
       run: SAMPLE="$SDK" TARGET="${SDK}ExampleSwift" scripts/setup_quickstart_framework.sh
     - name: Update Environment Variable For DynamicLinks
@@ -464,14 +460,13 @@ jobs:
       SDK: "Firestore"
     strategy:
       matrix:
-        os: [macos-13, macos-14]
         artifact: [Firebase-actions-dir, Firebase-actions-dir-dynamic]
-        include:
-          - os: macos-13
-            xcode: Xcode_15.2
+        build-env:
           - os: macos-14
-            xcode: Xcode_16
-    runs-on: ${{ matrix.os }}
+            xcode: Xcode_15.2
+          - os: macos-15
+            xcode: Xcode_16.1
+    runs-on: ${{ matrix.build-env.os }}
     steps:
     - uses: actions/checkout@v4
     - name: Get framework dir
@@ -493,7 +488,7 @@ jobs:
                                                "${HOME}"/ios_frameworks/Firebase/FirebaseAuth/* \
                                                "${HOME}"/ios_frameworks/Firebase/FirebaseAnalytics/*
     - name: Xcode
-      run: sudo xcode-select -s /Applications/${{ matrix.xcode }}.app/Contents/Developer
+      run: sudo xcode-select -s /Applications/${{ matrix.build-env.xcode }}.app/Contents/Developer
     - name: Install Secret GoogleService-Info.plist
       run: scripts/decrypt_gha_secret.sh scripts/gha-encrypted/qs-firestore.plist.gpg \
         quickstart-ios/firestore/GoogleService-Info.plist "$plist_secret"
@@ -505,7 +500,7 @@ jobs:
     - uses: actions/upload-artifact@v4
       if: ${{ failure() }}
       with:
-        name: quickstart_artifacts_firestore_${{ matrix.artifact }}_${{ matrix.os }}
+        name: quickstart_artifacts_firestore_${{ matrix.artifact }}_${{ matrix.build-env.os }}
         path: quickstart_artifacts_firestore.zip
 
   check_framework_firestore_symbols:
@@ -514,7 +509,7 @@ jobs:
     needs: package-head
     env:
       FIREBASECI_USE_LATEST_GOOGLEAPPMEASUREMENT: 1
-    runs-on: macos-13
+    runs-on: macos-14
     steps:
       - name: Xcode 15.2
         run: sudo xcode-select -s /Applications/Xcode_15.2.app/Contents/Developer
@@ -549,14 +544,13 @@ jobs:
       SDK: "InAppMessaging"
     strategy:
       matrix:
-        os: [macos-13, macos-14]
         artifact: [Firebase-actions-dir, Firebase-actions-dir-dynamic]
-        include:
-          - os: macos-13
-            xcode: Xcode_15.2
+        build-env:
           - os: macos-14
-            xcode: Xcode_16
-    runs-on: ${{ matrix.os }}
+            xcode: Xcode_15.2
+          - os: macos-15
+            xcode: Xcode_16.1
+    runs-on: ${{ matrix.build-env.os }}
     steps:
     - uses: actions/checkout@v4
     - name: Get framework dir
@@ -577,7 +571,7 @@ jobs:
                                                "${HOME}"/ios_frameworks/Firebase/FirebaseInAppMessaging/* \
                                                "${HOME}"/ios_frameworks/Firebase/FirebaseAnalytics/*
     - name: Xcode
-      run: sudo xcode-select -s /Applications/${{ matrix.xcode }}.app/Contents/Developer
+      run: sudo xcode-select -s /Applications/${{ matrix.build-env.xcode }}.app/Contents/Developer
     - name: Setup swift quickstart
       run: SAMPLE="$SDK" TARGET="${SDK}ExampleSwift" scripts/setup_quickstart_framework.sh
     - name: Install Secret GoogleService-Info.plist
@@ -606,14 +600,13 @@ jobs:
       SDK: "Messaging"
     strategy:
       matrix:
-        os: [macos-13, macos-14]
         artifact: [Firebase-actions-dir, Firebase-actions-dir-dynamic]
-        include:
-          - os: macos-13
-            xcode: Xcode_15.2
+        build-env:
           - os: macos-14
-            xcode: Xcode_16
-    runs-on: ${{ matrix.os }}
+            xcode: Xcode_15.2
+          - os: macos-15
+            xcode: Xcode_16.1
+    runs-on: ${{ matrix.build-env.os }}
     steps:
     - uses: actions/checkout@v4
     - name: Get framework dir
@@ -633,7 +626,7 @@ jobs:
                                                "${HOME}"/ios_frameworks/Firebase/FirebaseMessaging/* \
                                                "${HOME}"/ios_frameworks/Firebase/FirebaseAnalytics/*
     - name: Xcode
-      run: sudo xcode-select -s /Applications/${{ matrix.xcode }}.app/Contents/Developer
+      run: sudo xcode-select -s /Applications/${{ matrix.build-env.xcode }}.app/Contents/Developer
     - name: Setup swift quickstart
       run: SAMPLE="$SDK" TARGET="${SDK}ExampleSwift" scripts/setup_quickstart_framework.sh
     - name: Install Secret GoogleService-Info.plist
@@ -662,14 +655,13 @@ jobs:
       SDK: "Storage"
     strategy:
       matrix:
-        os: [macos-13, macos-14]
         artifact: [Firebase-actions-dir, Firebase-actions-dir-dynamic]
-        include:
-          - os: macos-13
-            xcode: Xcode_15.2
+        build-env:
           - os: macos-14
-            xcode: Xcode_16
-    runs-on: ${{ matrix.os }}
+            xcode: Xcode_15.2
+          - os: macos-15
+            xcode: Xcode_16.1
+    runs-on: ${{ matrix.build-env.os }}
     steps:
     - uses: actions/checkout@v4
     - name: Get framework dir
@@ -692,7 +684,7 @@ jobs:
                                                "${HOME}"/ios_frameworks/Firebase/FirebaseAuth/* \
                                                "${HOME}"/ios_frameworks/Firebase/FirebaseAnalytics/*
     - name: Xcode
-      run: sudo xcode-select -s /Applications/${{ matrix.xcode }}.app/Contents/Developer
+      run: sudo xcode-select -s /Applications/${{ matrix.build-env.xcode }}.app/Contents/Developer
     - name: Setup swift quickstart
       env:
         LEGACY: true
diff --git a/Firebase.podspec b/Firebase.podspec
index 50b992a43d1..c014f07db07 100644
--- a/Firebase.podspec
+++ b/Firebase.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'Firebase'
-  s.version          = '11.5.0'
+  s.version          = '11.6.0'
   s.summary          = 'Firebase'
 
   s.description      = <<-DESC
@@ -36,14 +36,14 @@ Simplify your app development, grow your user base, and monetize more effectivel
     ss.ios.deployment_target = '12.0'
     ss.osx.deployment_target = '10.15'
     ss.tvos.deployment_target = '13.0'
-    ss.ios.dependency 'FirebaseAnalytics', '~> 11.5.0'
-    ss.osx.dependency 'FirebaseAnalytics', '~> 11.5.0'
-    ss.tvos.dependency 'FirebaseAnalytics', '~> 11.5.0'
+    ss.ios.dependency 'FirebaseAnalytics', '~> 11.6.0'
+    ss.osx.dependency 'FirebaseAnalytics', '~> 11.6.0'
+    ss.tvos.dependency 'FirebaseAnalytics', '~> 11.6.0'
     ss.dependency 'Firebase/CoreOnly'
   end
 
   s.subspec 'CoreOnly' do |ss|
-    ss.dependency 'FirebaseCore', '11.5.0'
+    ss.dependency 'FirebaseCore', '~> 11.6.0'
     ss.source_files = 'CoreOnly/Sources/Firebase.h'
     ss.preserve_paths = 'CoreOnly/Sources/module.modulemap'
     if ENV['FIREBASE_POD_REPO_FOR_DEV_POD'] then
@@ -79,13 +79,13 @@ Simplify your app development, grow your user base, and monetize more effectivel
     ss.ios.deployment_target = '12.0'
     ss.osx.deployment_target = '10.15'
     ss.tvos.deployment_target = '13.0'
-    ss.dependency 'FirebaseAnalytics/WithoutAdIdSupport', '~> 11.5.0'
+    ss.dependency 'FirebaseAnalytics/WithoutAdIdSupport', '~> 11.6.0'
     ss.dependency 'Firebase/CoreOnly'
   end
 
   s.subspec 'ABTesting' do |ss|
     ss.dependency 'Firebase/CoreOnly'
-    ss.dependency 'FirebaseABTesting', '~> 11.5.0'
+    ss.dependency 'FirebaseABTesting', '~> 11.6.0'
     # Standard platforms PLUS watchOS.
     ss.ios.deployment_target = '13.0'
     ss.osx.deployment_target = '10.15'
@@ -95,13 +95,13 @@ Simplify your app development, grow your user base, and monetize more effectivel
 
   s.subspec 'AppDistribution' do |ss|
     ss.dependency 'Firebase/CoreOnly'
-    ss.ios.dependency 'FirebaseAppDistribution', '~> 11.5.0-beta'
+    ss.ios.dependency 'FirebaseAppDistribution', '~> 11.6.0-beta'
     ss.ios.deployment_target = '13.0'
   end
 
   s.subspec 'AppCheck' do |ss|
     ss.dependency 'Firebase/CoreOnly'
-    ss.dependency 'FirebaseAppCheck', '~> 11.5.0'
+    ss.dependency 'FirebaseAppCheck', '~> 11.6.0'
     ss.ios.deployment_target = '13.0'
     ss.osx.deployment_target = '10.15'
     ss.tvos.deployment_target = '13.0'
@@ -110,7 +110,7 @@ Simplify your app development, grow your user base, and monetize more effectivel
 
   s.subspec 'Auth' do |ss|
     ss.dependency 'Firebase/CoreOnly'
-    ss.dependency 'FirebaseAuth', '~> 11.5.0'
+    ss.dependency 'FirebaseAuth', '~> 11.6.0'
     # Standard platforms PLUS watchOS.
     ss.ios.deployment_target = '13.0'
     ss.osx.deployment_target = '10.15'
@@ -120,7 +120,7 @@ Simplify your app development, grow your user base, and monetize more effectivel
 
   s.subspec 'Crashlytics' do |ss|
     ss.dependency 'Firebase/CoreOnly'
-    ss.dependency 'FirebaseCrashlytics', '~> 11.5.0'
+    ss.dependency 'FirebaseCrashlytics', '~> 11.6.0'
     # Standard platforms PLUS watchOS.
     ss.ios.deployment_target = '12.0'
     ss.osx.deployment_target = '10.15'
@@ -130,7 +130,7 @@ Simplify your app development, grow your user base, and monetize more effectivel
 
   s.subspec 'Database' do |ss|
     ss.dependency 'Firebase/CoreOnly'
-    ss.dependency 'FirebaseDatabase', '~> 11.5.0'
+    ss.dependency 'FirebaseDatabase', '~> 11.6.0'
     # Standard platforms PLUS watchOS 7.
     ss.ios.deployment_target = '13.0'
     ss.osx.deployment_target = '10.15'
@@ -140,13 +140,13 @@ Simplify your app development, grow your user base, and monetize more effectivel
 
   s.subspec 'DynamicLinks' do |ss|
     ss.dependency 'Firebase/CoreOnly'
-    ss.ios.dependency 'FirebaseDynamicLinks', '~> 11.5.0'
+    ss.ios.dependency 'FirebaseDynamicLinks', '~> 11.6.0'
     ss.ios.deployment_target = '13.0'
   end
 
   s.subspec 'Firestore' do |ss|
     ss.dependency 'Firebase/CoreOnly'
-    ss.dependency 'FirebaseFirestore', '~> 11.5.0'
+    ss.dependency 'FirebaseFirestore', '~> 11.6.0'
     ss.ios.deployment_target = '13.0'
     ss.osx.deployment_target = '10.15'
     ss.tvos.deployment_target = '13.0'
@@ -154,7 +154,7 @@ Simplify your app development, grow your user base, and monetize more effectivel
 
   s.subspec 'Functions' do |ss|
     ss.dependency 'Firebase/CoreOnly'
-    ss.dependency 'FirebaseFunctions', '~> 11.5.0'
+    ss.dependency 'FirebaseFunctions', '~> 11.6.0'
     # Standard platforms PLUS watchOS.
     ss.ios.deployment_target = '13.0'
     ss.osx.deployment_target = '10.15'
@@ -164,20 +164,20 @@ Simplify your app development, grow your user base, and monetize more effectivel
 
   s.subspec 'InAppMessaging' do |ss|
     ss.dependency 'Firebase/CoreOnly'
-    ss.ios.dependency 'FirebaseInAppMessaging', '~> 11.5.0-beta'
-    ss.tvos.dependency 'FirebaseInAppMessaging', '~> 11.5.0-beta'
+    ss.ios.dependency 'FirebaseInAppMessaging', '~> 11.6.0-beta'
+    ss.tvos.dependency 'FirebaseInAppMessaging', '~> 11.6.0-beta'
     ss.ios.deployment_target = '13.0'
     ss.tvos.deployment_target = '13.0'
   end
 
   s.subspec 'Installations' do |ss|
     ss.dependency 'Firebase/CoreOnly'
-    ss.dependency 'FirebaseInstallations', '~> 11.5.0'
+    ss.dependency 'FirebaseInstallations', '~> 11.6.0'
   end
 
   s.subspec 'Messaging' do |ss|
     ss.dependency 'Firebase/CoreOnly'
-    ss.dependency 'FirebaseMessaging', '~> 11.5.0'
+    ss.dependency 'FirebaseMessaging', '~> 11.6.0'
     # Standard platforms PLUS watchOS.
     ss.ios.deployment_target = '13.0'
     ss.osx.deployment_target = '10.15'
@@ -187,7 +187,7 @@ Simplify your app development, grow your user base, and monetize more effectivel
 
   s.subspec 'MLModelDownloader' do |ss|
     ss.dependency 'Firebase/CoreOnly'
-    ss.dependency 'FirebaseMLModelDownloader', '~> 11.5.0-beta'
+    ss.dependency 'FirebaseMLModelDownloader', '~> 11.6.0-beta'
     # Standard platforms PLUS watchOS.
     ss.ios.deployment_target = '13.0'
     ss.osx.deployment_target = '10.15'
@@ -197,15 +197,15 @@ Simplify your app development, grow your user base, and monetize more effectivel
 
   s.subspec 'Performance' do |ss|
     ss.dependency 'Firebase/CoreOnly'
-    ss.ios.dependency 'FirebasePerformance', '~> 11.5.0'
-    ss.tvos.dependency 'FirebasePerformance', '~> 11.5.0'
+    ss.ios.dependency 'FirebasePerformance', '~> 11.6.0'
+    ss.tvos.dependency 'FirebasePerformance', '~> 11.6.0'
     ss.ios.deployment_target = '13.0'
     ss.tvos.deployment_target = '13.0'
   end
 
   s.subspec 'RemoteConfig' do |ss|
     ss.dependency 'Firebase/CoreOnly'
-    ss.dependency 'FirebaseRemoteConfig', '~> 11.5.0'
+    ss.dependency 'FirebaseRemoteConfig', '~> 11.6.0'
     # Standard platforms PLUS watchOS.
     ss.ios.deployment_target = '13.0'
     ss.osx.deployment_target = '10.15'
@@ -215,7 +215,7 @@ Simplify your app development, grow your user base, and monetize more effectivel
 
   s.subspec 'Storage' do |ss|
     ss.dependency 'Firebase/CoreOnly'
-    ss.dependency 'FirebaseStorage', '~> 11.5.0'
+    ss.dependency 'FirebaseStorage', '~> 11.6.0'
     # Standard platforms PLUS watchOS.
     ss.ios.deployment_target = '13.0'
     ss.osx.deployment_target = '10.15'
diff --git a/FirebaseABTesting.podspec b/FirebaseABTesting.podspec
index d988bbac272..76a3c6eacc6 100644
--- a/FirebaseABTesting.podspec
+++ b/FirebaseABTesting.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseABTesting'
-  s.version          = '11.5.0'
+  s.version          = '11.6.0'
   s.summary          = 'Firebase ABTesting'
 
   s.description      = <<-DESC
@@ -52,7 +52,7 @@ Firebase Cloud Messaging and Firebase Remote Config in your app.
     'GCC_C_LANGUAGE_STANDARD' => 'c99',
     'HEADER_SEARCH_PATHS' => '"${PODS_TARGET_SRCROOT}"'
   }
-  s.dependency 'FirebaseCore', '11.5'
+  s.dependency 'FirebaseCore', '~> 11.6.0'
 
   s.test_spec 'unit' do |unit_tests|
     unit_tests.scheme = { :code_coverage => true }
diff --git a/FirebaseAnalytics.podspec b/FirebaseAnalytics.podspec
index 125dd7e6f01..9e109930a87 100644
--- a/FirebaseAnalytics.podspec
+++ b/FirebaseAnalytics.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
     s.name             = 'FirebaseAnalytics'
-    s.version          = '11.5.0'
+    s.version          = '11.6.0'
     s.summary          = 'Firebase Analytics for iOS'
 
     s.description      = <<-DESC
@@ -26,7 +26,7 @@ Pod::Spec.new do |s|
     s.libraries  = 'c++', 'sqlite3', 'z'
     s.frameworks = 'StoreKit'
 
-    s.dependency 'FirebaseCore', '11.5'
+    s.dependency 'FirebaseCore', '~> 11.6.0'
     s.dependency 'FirebaseInstallations', '~> 11.0'
     s.dependency 'GoogleUtilities/AppDelegateSwizzler', '~> 8.0'
     s.dependency 'GoogleUtilities/MethodSwizzler', '~> 8.0'
@@ -37,12 +37,12 @@ Pod::Spec.new do |s|
     s.default_subspecs = 'AdIdSupport'
 
     s.subspec 'AdIdSupport' do |ss|
-        ss.dependency 'GoogleAppMeasurement', '11.5.0'
+        ss.dependency 'GoogleAppMeasurement', '11.6.0'
         ss.vendored_frameworks = 'Frameworks/FirebaseAnalytics.xcframework'
     end
 
     s.subspec 'WithoutAdIdSupport' do |ss|
-        ss.dependency 'GoogleAppMeasurement/WithoutAdIdSupport', '11.5.0'
+        ss.dependency 'GoogleAppMeasurement/WithoutAdIdSupport', '11.6.0'
         ss.vendored_frameworks = 'Frameworks/FirebaseAnalytics.xcframework'
     end
 
diff --git a/FirebaseAnalyticsOnDeviceConversion.podspec b/FirebaseAnalyticsOnDeviceConversion.podspec
index e03608aa555..4d57ab96f1b 100644
--- a/FirebaseAnalyticsOnDeviceConversion.podspec
+++ b/FirebaseAnalyticsOnDeviceConversion.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
     s.name             = 'FirebaseAnalyticsOnDeviceConversion'
-    s.version          = '11.5.0'
+    s.version          = '11.6.0'
     s.summary          = 'On device conversion measurement plugin for FirebaseAnalytics. Not intended for direct use.'
 
     s.description      = <<-DESC
@@ -18,7 +18,7 @@ Pod::Spec.new do |s|
 
     s.cocoapods_version = '>= 1.12.0'
 
-    s.dependency 'GoogleAppMeasurementOnDeviceConversion', '11.5.0'
+    s.dependency 'GoogleAppMeasurementOnDeviceConversion', '11.6.0'
 
     s.static_framework = true
 
diff --git a/FirebaseAppCheck.podspec b/FirebaseAppCheck.podspec
index a80ebd8451a..7f8995ac47c 100644
--- a/FirebaseAppCheck.podspec
+++ b/FirebaseAppCheck.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseAppCheck'
-  s.version          = '11.5.0'
+  s.version          = '11.6.0'
   s.summary          = 'Firebase App Check SDK.'
 
   s.description      = <<-DESC
@@ -46,7 +46,7 @@ Pod::Spec.new do |s|
 
   s.dependency 'AppCheckCore', '~> 11.0'
   s.dependency 'FirebaseAppCheckInterop', '~> 11.0'
-  s.dependency 'FirebaseCore', '11.5'
+  s.dependency 'FirebaseCore', '~> 11.6.0'
   s.dependency 'GoogleUtilities/Environment', '~> 8.0'
   s.dependency 'GoogleUtilities/UserDefaults', '~> 8.0'
 
diff --git a/FirebaseAppCheckInterop.podspec b/FirebaseAppCheckInterop.podspec
index 0496fe9832b..fe888c5a945 100644
--- a/FirebaseAppCheckInterop.podspec
+++ b/FirebaseAppCheckInterop.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseAppCheckInterop'
-  s.version          = '11.5.0'
+  s.version          = '11.6.0'
   s.summary          = 'Interfaces that allow other Firebase SDKs to use AppCheck functionality.'
 
   s.description      = <<-DESC
diff --git a/FirebaseAppDistribution.podspec b/FirebaseAppDistribution.podspec
index c5230bda665..647a88b941c 100644
--- a/FirebaseAppDistribution.podspec
+++ b/FirebaseAppDistribution.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseAppDistribution'
-  s.version          = '11.5.0-beta'
+  s.version          = '11.6.0-beta'
   s.summary          = 'App Distribution for Firebase iOS SDK.'
 
   s.description      = <<-DESC
@@ -30,7 +30,7 @@ iOS SDK for App Distribution for Firebase.
   ]
   s.public_header_files = base_dir + 'Public/FirebaseAppDistribution/*.h'
 
-  s.dependency 'FirebaseCore', '11.5'
+  s.dependency 'FirebaseCore', '~> 11.6.0'
   s.dependency 'GoogleUtilities/AppDelegateSwizzler', '~> 8.0'
   s.dependency 'GoogleUtilities/UserDefaults', '~> 8.0'
   s.dependency 'FirebaseInstallations', '~> 11.0'
diff --git a/FirebaseAuth.podspec b/FirebaseAuth.podspec
index 67f32a30b74..bdb9ee26263 100644
--- a/FirebaseAuth.podspec
+++ b/FirebaseAuth.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseAuth'
-  s.version          = '11.5.0'
+  s.version          = '11.6.0'
   s.summary          = 'Apple platform client for Firebase Authentication'
 
   s.description      = <<-DESC
@@ -58,8 +58,8 @@ supports email and password accounts, as well as several 3rd party authenticatio
   s.ios.framework = 'SafariServices'
   s.dependency 'FirebaseAuthInterop', '~> 11.0'
   s.dependency 'FirebaseAppCheckInterop', '~> 11.0'
-  s.dependency 'FirebaseCore', '11.5'
-  s.dependency 'FirebaseCoreExtension', '11.5'
+  s.dependency 'FirebaseCore', '~> 11.6.0'
+  s.dependency 'FirebaseCoreExtension', '~> 11.6.0'
   s.dependency 'GoogleUtilities/AppDelegateSwizzler', '~> 8.0'
   s.dependency 'GoogleUtilities/Environment', '~> 8.0'
   s.dependency 'GTMSessionFetcher/Core', '>= 3.4', '< 5.0'
diff --git a/FirebaseAuth/Sources/Swift/Auth/Auth.swift b/FirebaseAuth/Sources/Swift/Auth/Auth.swift
index 19e8029974b..e5ccdaafac7 100644
--- a/FirebaseAuth/Sources/Swift/Auth/Auth.swift
+++ b/FirebaseAuth/Sources/Swift/Auth/Auth.swift
@@ -123,11 +123,12 @@ extension Auth: AuthInterop {
         return
       }
       // Call back with current user token.
-      currentUser.internalGetToken(forceRefresh: forceRefresh) { token, error in
-        DispatchQueue.main.async {
-          callback(token, error)
+      currentUser
+        .internalGetToken(forceRefresh: forceRefresh, backend: strongSelf.backend) { token, error in
+          DispatchQueue.main.async {
+            callback(token, error)
+          }
         }
-      }
     }
   }
 
@@ -292,7 +293,7 @@ extension Auth: AuthInterop {
                                          requestConfiguration: self.requestConfiguration)
       Task {
         do {
-          let response = try await AuthBackend.call(with: request)
+          let response = try await self.backend.call(with: request)
           Auth.wrapMainAsync(callback: completion, withParam: response.signinMethods, error: nil)
         } catch {
           Auth.wrapMainAsync(callback: completion, withParam: nil, error: error)
@@ -395,7 +396,7 @@ extension Auth: AuthInterop {
       let response = try await injectRecaptcha(request: request,
                                                action: AuthRecaptchaAction.signInWithPassword)
     #else
-      let response = try await AuthBackend.call(with: request)
+      let response = try await backend.call(with: request)
     #endif
     return try await completeSignIn(
       withAccessToken: response.idToken,
@@ -709,7 +710,7 @@ extension Auth: AuthInterop {
       let request = SignUpNewUserRequest(requestConfiguration: self.requestConfiguration)
       Task {
         do {
-          let response = try await AuthBackend.call(with: request)
+          let response = try await self.backend.call(with: request)
           let user = try await self.completeSignIn(
             withAccessToken: response.idToken,
             accessTokenExpirationDate: response.approximateExpirationDate,
@@ -771,7 +772,7 @@ extension Auth: AuthInterop {
                                              requestConfiguration: self.requestConfiguration)
       Task {
         do {
-          let response = try await AuthBackend.call(with: request)
+          let response = try await self.backend.call(with: request)
           let user = try await self.completeSignIn(
             withAccessToken: response.idToken,
             accessTokenExpirationDate: response.approximateExpirationDate,
@@ -881,7 +882,7 @@ extension Auth: AuthInterop {
         if let inResponse {
           response = inResponse
         } else {
-          response = try await AuthBackend.call(with: request)
+          response = try await self.backend.call(with: request)
         }
         let user = try await self.completeSignIn(
           withAccessToken: response.idToken,
@@ -993,7 +994,7 @@ extension Auth: AuthInterop {
                                          requestConfiguration: self.requestConfiguration)
       Task {
         do {
-          let response = try await AuthBackend.call(with: request)
+          let response = try await self.backend.call(with: request)
 
           let operation = ActionCodeInfo.actionCodeOperation(forRequestType: response.requestType)
           guard let email = response.email else {
@@ -1433,7 +1434,7 @@ extension Auth: AuthInterop {
   /// complete, or fails. Invoked asynchronously on the main thread in the future.
   @objc open func revokeToken(withAuthorizationCode authorizationCode: String,
                               completion: ((Error?) -> Void)? = nil) {
-    currentUser?.internalGetToken { idToken, error in
+    currentUser?.internalGetToken(backend: backend) { idToken, error in
       if let error {
         Auth.wrapMainAsync(completion, error)
         return
@@ -1613,7 +1614,9 @@ extension Auth: AuthInterop {
 
   // MARK: Internal methods
 
-  init(app: FirebaseApp, keychainStorageProvider: AuthKeychainStorage = AuthKeychainStorageReal()) {
+  init(app: FirebaseApp,
+       keychainStorageProvider: AuthKeychainStorage = AuthKeychainStorageReal(),
+       backend: AuthBackend = AuthBackend(rpcIssuer: AuthBackendRPCIssuer())) {
     Auth.setKeychainServiceNameForApp(app)
     self.app = app
     mainBundleUrlTypes = Bundle.main
@@ -1638,6 +1641,7 @@ extension Auth: AuthInterop {
                                                     auth: nil,
                                                     heartbeatLogger: app.heartbeatLogger,
                                                     appCheck: appCheck)
+    self.backend = backend
     super.init()
     requestConfiguration.auth = self
 
@@ -1911,17 +1915,18 @@ extension Auth: AuthInterop {
         return
       }
       let uid = strongSelf.currentUser?.uid
-      strongSelf.currentUser?.internalGetToken(forceRefresh: true) { token, error in
-        if strongSelf.currentUser?.uid != uid {
-          return
-        }
-        if error != nil {
-          // Kicks off exponential back off logic to retry failed attempt. Starts with one minute
-          // delay (60 seconds) if this is the first failed attempt.
-          let rescheduleDelay = retry ? min(delay * 2, 16 * 60) : 60
-          strongSelf.scheduleAutoTokenRefresh(withDelay: rescheduleDelay, retry: true)
+      strongSelf.currentUser?
+        .internalGetToken(forceRefresh: true, backend: strongSelf.backend) { token, error in
+          if strongSelf.currentUser?.uid != uid {
+            return
+          }
+          if error != nil {
+            // Kicks off exponential back off logic to retry failed attempt. Starts with one minute
+            // delay (60 seconds) if this is the first failed attempt.
+            let rescheduleDelay = retry ? min(delay * 2, 16 * 60) : 60
+            strongSelf.scheduleAutoTokenRefresh(withDelay: rescheduleDelay, retry: true)
+          }
         }
-      }
     }
   }
 
@@ -2075,7 +2080,7 @@ extension Auth: AuthInterop {
                                          requestConfiguration: requestConfiguration)
     request.autoCreate = !isReauthentication
     credential.prepare(request)
-    let response = try await AuthBackend.call(with: request)
+    let response = try await backend.call(with: request)
     if response.needConfirmation {
       let email = response.email
       let credential = OAuthCredential(withVerifyAssertionResponse: response)
@@ -2114,7 +2119,7 @@ extension Auth: AuthInterop {
                                                phoneNumber: phoneNumber,
                                                operation: operation,
                                                requestConfiguration: requestConfiguration)
-        return try await AuthBackend.call(with: request)
+        return try await backend.call(with: request)
       case let .verification(verificationID, code):
         guard verificationID.count > 0 else {
           throw AuthErrorUtils.missingVerificationIDError(message: nil)
@@ -2126,7 +2131,7 @@ extension Auth: AuthInterop {
                                                verificationCode: code,
                                                operation: operation,
                                                requestConfiguration: requestConfiguration)
-        return try await AuthBackend.call(with: request)
+        return try await backend.call(with: request)
       }
     }
   #endif
@@ -2152,7 +2157,7 @@ extension Auth: AuthInterop {
                                                 timestamp: credential.timestamp,
                                                 displayName: credential.displayName,
                                                 requestConfiguration: requestConfiguration)
-      let response = try await AuthBackend.call(with: request)
+      let response = try await backend.call(with: request)
       let user = try await completeSignIn(withAccessToken: response.idToken,
                                           accessTokenExpirationDate: response
                                             .approximateExpirationDate,
@@ -2184,7 +2189,7 @@ extension Auth: AuthInterop {
     let request = EmailLinkSignInRequest(email: email,
                                          oobCode: actionCode,
                                          requestConfiguration: requestConfiguration)
-    let response = try await AuthBackend.call(with: request)
+    let response = try await backend.call(with: request)
     let user = try await completeSignIn(withAccessToken: response.idToken,
                                         accessTokenExpirationDate: response
                                           .approximateExpirationDate,
@@ -2242,7 +2247,7 @@ extension Auth: AuthInterop {
   private func wrapAsyncRPCTask(_ request: any AuthRPCRequest, _ callback: ((Error?) -> Void)?) {
     Task {
       do {
-        let _ = try await AuthBackend.call(with: request)
+        let _ = try await self.backend.call(with: request)
         Auth.wrapMainAsync(callback, nil)
       } catch {
         Auth.wrapMainAsync(callback, error)
@@ -2294,7 +2299,7 @@ extension Auth: AuthInterop {
                                                           action: action)
       } else {
         do {
-          return try await AuthBackend.call(with: request)
+          return try await backend.call(with: request)
         } catch {
           let nsError = error as NSError
           if let underlyingError = nsError.userInfo[NSUnderlyingErrorKey] as? NSError,
@@ -2313,7 +2318,7 @@ extension Auth: AuthInterop {
           }
         }
       }
-      return try await AuthBackend.call(with: request)
+      return try await backend.call(with: request)
     }
   #endif
 
@@ -2330,6 +2335,8 @@ extension Auth: AuthInterop {
   ///   Auth's backend.
   var requestConfiguration: AuthRequestConfiguration
 
+  let backend: AuthBackend
+
   #if os(iOS)
 
     /// The manager for APNs tokens used by phone number auth.
diff --git a/FirebaseAuth/Sources/Swift/AuthProvider/AuthCredential.swift b/FirebaseAuth/Sources/Swift/AuthProvider/AuthCredential.swift
index 0500875b10f..2ae683ae22b 100644
--- a/FirebaseAuth/Sources/Swift/AuthProvider/AuthCredential.swift
+++ b/FirebaseAuth/Sources/Swift/AuthProvider/AuthCredential.swift
@@ -16,7 +16,7 @@ import Foundation
 
 /// Public representation of a credential.
 @available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
-@objc(FIRAuthCredential) open class AuthCredential: NSObject {
+@objc(FIRAuthCredential) open class AuthCredential: NSObject, @unchecked Sendable {
   /// The name of the identity provider for the credential.
   @objc public let provider: String
 
diff --git a/FirebaseAuth/Sources/Swift/AuthProvider/EmailAuthProvider.swift b/FirebaseAuth/Sources/Swift/AuthProvider/EmailAuthProvider.swift
index 050dce30974..e87445b84a2 100644
--- a/FirebaseAuth/Sources/Swift/AuthProvider/EmailAuthProvider.swift
+++ b/FirebaseAuth/Sources/Swift/AuthProvider/EmailAuthProvider.swift
@@ -38,7 +38,8 @@ import Foundation
 }
 
 @available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
-@objc(FIREmailPasswordAuthCredential) class EmailAuthCredential: AuthCredential, NSSecureCoding {
+@objc(FIREmailPasswordAuthCredential) class EmailAuthCredential: AuthCredential, NSSecureCoding,
+  @unchecked Sendable {
   let email: String
 
   enum EmailType {
diff --git a/FirebaseAuth/Sources/Swift/AuthProvider/FacebookAuthProvider.swift b/FirebaseAuth/Sources/Swift/AuthProvider/FacebookAuthProvider.swift
index cc89e7b3394..59cb2385425 100644
--- a/FirebaseAuth/Sources/Swift/AuthProvider/FacebookAuthProvider.swift
+++ b/FirebaseAuth/Sources/Swift/AuthProvider/FacebookAuthProvider.swift
@@ -34,7 +34,8 @@ import Foundation
 }
 
 @available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
-@objc(FIRFacebookAuthCredential) class FacebookAuthCredential: AuthCredential, NSSecureCoding {
+@objc(FIRFacebookAuthCredential) class FacebookAuthCredential: AuthCredential, NSSecureCoding,
+  @unchecked Sendable {
   let accessToken: String
 
   init(withAccessToken accessToken: String) {
diff --git a/FirebaseAuth/Sources/Swift/AuthProvider/GameCenterAuthProvider.swift b/FirebaseAuth/Sources/Swift/AuthProvider/GameCenterAuthProvider.swift
index 4560bad9aaf..82836ee81b0 100644
--- a/FirebaseAuth/Sources/Swift/AuthProvider/GameCenterAuthProvider.swift
+++ b/FirebaseAuth/Sources/Swift/AuthProvider/GameCenterAuthProvider.swift
@@ -129,7 +129,7 @@
 
   @available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
   @objc(FIRGameCenterAuthCredential)
-  class GameCenterAuthCredential: AuthCredential, NSSecureCoding {
+  class GameCenterAuthCredential: AuthCredential, NSSecureCoding, @unchecked Sendable {
     let playerID: String
     let teamPlayerID: String?
     let gamePlayerID: String?
diff --git a/FirebaseAuth/Sources/Swift/AuthProvider/GitHubAuthProvider.swift b/FirebaseAuth/Sources/Swift/AuthProvider/GitHubAuthProvider.swift
index 801e63fa8ee..75b914cbb7a 100644
--- a/FirebaseAuth/Sources/Swift/AuthProvider/GitHubAuthProvider.swift
+++ b/FirebaseAuth/Sources/Swift/AuthProvider/GitHubAuthProvider.swift
@@ -34,7 +34,8 @@ import Foundation
 }
 
 @available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
-@objc(FIRGitHubAuthCredential) class GitHubAuthCredential: AuthCredential, NSSecureCoding {
+@objc(FIRGitHubAuthCredential) class GitHubAuthCredential: AuthCredential, NSSecureCoding,
+  @unchecked Sendable {
   let token: String
 
   init(withToken token: String) {
diff --git a/FirebaseAuth/Sources/Swift/AuthProvider/GoogleAuthProvider.swift b/FirebaseAuth/Sources/Swift/AuthProvider/GoogleAuthProvider.swift
index 41f223b25dc..0f41ac69ce3 100644
--- a/FirebaseAuth/Sources/Swift/AuthProvider/GoogleAuthProvider.swift
+++ b/FirebaseAuth/Sources/Swift/AuthProvider/GoogleAuthProvider.swift
@@ -36,7 +36,8 @@ import Foundation
 }
 
 @available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
-@objc(FIRGoogleAuthCredential) class GoogleAuthCredential: AuthCredential, NSSecureCoding {
+@objc(FIRGoogleAuthCredential) class GoogleAuthCredential: AuthCredential, NSSecureCoding,
+  @unchecked Sendable {
   let idToken: String
   let accessToken: String
 
diff --git a/FirebaseAuth/Sources/Swift/AuthProvider/OAuthCredential.swift b/FirebaseAuth/Sources/Swift/AuthProvider/OAuthCredential.swift
index 920fd138af4..8029fd6df51 100644
--- a/FirebaseAuth/Sources/Swift/AuthProvider/OAuthCredential.swift
+++ b/FirebaseAuth/Sources/Swift/AuthProvider/OAuthCredential.swift
@@ -16,7 +16,8 @@ import Foundation
 
 /// Internal implementation of `AuthCredential` for generic credentials.
 @available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
-@objc(FIROAuthCredential) open class OAuthCredential: AuthCredential, NSSecureCoding {
+@objc(FIROAuthCredential) open class OAuthCredential: AuthCredential, NSSecureCoding,
+  @unchecked Sendable {
   /// The ID Token associated with this credential.
   @objc(IDToken) public let idToken: String?
 
diff --git a/FirebaseAuth/Sources/Swift/AuthProvider/OAuthProvider.swift b/FirebaseAuth/Sources/Swift/AuthProvider/OAuthProvider.swift
index 01437d49891..b8cca1f5fca 100644
--- a/FirebaseAuth/Sources/Swift/AuthProvider/OAuthProvider.swift
+++ b/FirebaseAuth/Sources/Swift/AuthProvider/OAuthProvider.swift
@@ -413,7 +413,7 @@ import Foundation
   private func getHeadfulLiteUrl(eventID: String,
                                  sessionID: String) async throws -> URL? {
     let authDomain = try await AuthWebUtils
-      .fetchAuthDomain(withRequestConfiguration: auth.requestConfiguration)
+      .fetchAuthDomain(withRequestConfiguration: auth.requestConfiguration, backend: auth.backend)
     let bundleID = Bundle.main.bundleIdentifier
     let clientID = auth.app?.options.clientID
     let appID = auth.app?.options.googleAppID
diff --git a/FirebaseAuth/Sources/Swift/AuthProvider/PhoneAuthCredential.swift b/FirebaseAuth/Sources/Swift/AuthProvider/PhoneAuthCredential.swift
index 49f643a34d1..a930fadc2eb 100644
--- a/FirebaseAuth/Sources/Swift/AuthProvider/PhoneAuthCredential.swift
+++ b/FirebaseAuth/Sources/Swift/AuthProvider/PhoneAuthCredential.swift
@@ -18,7 +18,8 @@ import Foundation
 ///
 /// This class is available on iOS only.
 @available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
-@objc(FIRPhoneAuthCredential) open class PhoneAuthCredential: AuthCredential, NSSecureCoding {
+@objc(FIRPhoneAuthCredential) open class PhoneAuthCredential: AuthCredential, NSSecureCoding,
+  @unchecked Sendable {
   enum CredentialKind {
     case phoneNumber(_ phoneNumber: String, _ temporaryProof: String)
     case verification(_ id: String, _ code: String)
diff --git a/FirebaseAuth/Sources/Swift/AuthProvider/PhoneAuthProvider.swift b/FirebaseAuth/Sources/Swift/AuthProvider/PhoneAuthProvider.swift
index 32d15499f74..2a1de385aa4 100644
--- a/FirebaseAuth/Sources/Swift/AuthProvider/PhoneAuthProvider.swift
+++ b/FirebaseAuth/Sources/Swift/AuthProvider/PhoneAuthProvider.swift
@@ -217,7 +217,7 @@ import Foundation
                                                   .requestConfiguration)
 
       do {
-        let response = try await AuthBackend.call(with: request)
+        let response = try await auth.backend.call(with: request)
         return response.verificationID
       } catch {
         return try await handleVerifyErrorWithRetry(error: error,
@@ -245,7 +245,7 @@ import Foundation
           requestConfiguration: auth.requestConfiguration
         )
 
-        let response = try await AuthBackend.call(with: request)
+        let response = try await auth.backend.call(with: request)
         return response.verificationID
       }
       guard let session else {
@@ -263,7 +263,7 @@ import Foundation
           let request = StartMFAEnrollmentRequest(idToken: idToken,
                                                   enrollmentInfo: startMFARequestInfo,
                                                   requestConfiguration: auth.requestConfiguration)
-          let response = try await AuthBackend.call(with: request)
+          let response = try await auth.backend.call(with: request)
           return response.phoneSessionInfo?.sessionInfo
         } else {
           let request = StartMFASignInRequest(MFAPendingCredential: session.mfaPendingCredential,
@@ -271,7 +271,7 @@ import Foundation
                                               signInInfo: startMFARequestInfo,
                                               requestConfiguration: auth.requestConfiguration)
 
-          let response = try await AuthBackend.call(with: request)
+          let response = try await auth.backend.call(with: request)
           return response.responseInfo?.sessionInfo
         }
       } catch {
@@ -328,7 +328,7 @@ import Foundation
                                         isSandbox: token.type == AuthAPNSTokenType.sandbox,
                                         requestConfiguration: auth.requestConfiguration)
       do {
-        let verifyResponse = try await AuthBackend.call(with: request)
+        let verifyResponse = try await auth.backend.call(with: request)
         guard let receipt = verifyResponse.receipt,
               let timeout = verifyResponse.suggestedTimeOutDate?.timeIntervalSinceNow else {
           fatalError("Internal Auth Error: invalid VerifyClientResponse")
@@ -436,7 +436,7 @@ import Foundation
     /// - Parameter eventID: The event ID used for this purpose.
     private func reCAPTCHAURL(withEventID eventID: String) async throws -> URL? {
       let authDomain = try await AuthWebUtils
-        .fetchAuthDomain(withRequestConfiguration: auth.requestConfiguration)
+        .fetchAuthDomain(withRequestConfiguration: auth.requestConfiguration, backend: auth.backend)
       let bundleID = Bundle.main.bundleIdentifier
       let clientID = auth.app?.options.clientID
       let appID = auth.app?.options.googleAppID
diff --git a/FirebaseAuth/Sources/Swift/AuthProvider/TwitterAuthProvider.swift b/FirebaseAuth/Sources/Swift/AuthProvider/TwitterAuthProvider.swift
index 6364241188f..f9c32f9d5ad 100644
--- a/FirebaseAuth/Sources/Swift/AuthProvider/TwitterAuthProvider.swift
+++ b/FirebaseAuth/Sources/Swift/AuthProvider/TwitterAuthProvider.swift
@@ -35,7 +35,8 @@ import Foundation
 }
 
 @available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
-@objc(FIRTwitterAuthCredential) class TwitterAuthCredential: AuthCredential, NSSecureCoding {
+@objc(FIRTwitterAuthCredential) class TwitterAuthCredential: AuthCredential, NSSecureCoding,
+  @unchecked Sendable {
   let token: String
   let secret: String
 
diff --git a/FirebaseAuth/Sources/Swift/Backend/AuthBackend.swift b/FirebaseAuth/Sources/Swift/Backend/AuthBackend.swift
index 58fb6c4be80..85802392052 100644
--- a/FirebaseAuth/Sources/Swift/Backend/AuthBackend.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/AuthBackend.swift
@@ -32,21 +32,7 @@ class AuthBackend: AuthBackendProtocol {
     return "FirebaseAuth.iOS/\(FirebaseVersion()) \(GTMFetcherStandardUserAgentString(nil))"
   }
 
-  static func call<T: AuthRPCRequest>(with request: T) async throws -> T.Response {
-    return try await shared.call(with: request)
-  }
-
-  static func setTestRPCIssuer(issuer: AuthBackendRPCIssuer) {
-    shared.rpcIssuer = issuer
-  }
-
-  static func resetRPCIssuer() {
-    shared.rpcIssuer = AuthBackendRPCIssuer()
-  }
-
-  private static let shared: AuthBackend = .init(rpcIssuer: AuthBackendRPCIssuer())
-
-  private var rpcIssuer: any AuthBackendRPCIssuerProtocol
+  private let rpcIssuer: any AuthBackendRPCIssuerProtocol
 
   init(rpcIssuer: any AuthBackendRPCIssuerProtocol) {
     self.rpcIssuer = rpcIssuer
@@ -251,66 +237,74 @@ class AuthBackend: AuthBackendProtocol {
     }
     dictionary = decodedDictionary
 
-    var response = T.Response()
+    let responseResult = Result {
+      try T.Response(dictionary: dictionary)
+    }
 
     // At this point we either have an error with successfully decoded
     // details in the body, or we have a response which must pass further
     // validation before we know it's truly successful. We deal with the
     // case where we have an error with successfully decoded error details
     // first:
-    if error != nil {
-      if let errorDictionary = dictionary["error"] as? [String: AnyHashable] {
-        if let errorMessage = errorDictionary["message"] as? String {
-          if let clientError = Self.clientError(
-            withServerErrorMessage: errorMessage,
-            errorDictionary: errorDictionary,
-            response: response,
-            error: error
-          ) {
-            throw clientError
+    switch responseResult {
+    case let .success(response):
+      try propagateError(error, dictionary: dictionary, response: response)
+      // In case returnIDPCredential of a verifyAssertion request is set to
+      // @YES, the server may return a 200 with a response that may contain a
+      // server error.
+      if let verifyAssertionRequest = request as? VerifyAssertionRequest {
+        if verifyAssertionRequest.returnIDPCredential {
+          if let errorMessage = dictionary["errorMessage"] as? String {
+            if let clientError = Self.clientError(
+              withServerErrorMessage: errorMessage,
+              errorDictionary: dictionary,
+              response: response,
+              error: error
+            ) {
+              throw clientError
+            }
           }
         }
-        // Not a message we know, return the message directly.
-        throw AuthErrorUtils.unexpectedErrorResponse(
-          deserializedResponse: errorDictionary,
-          underlyingError: error
-        )
       }
-      // No error message at all, return the decoded response.
+      return response
+    case let .failure(failure):
+      try propagateError(error, dictionary: dictionary, response: nil)
       throw AuthErrorUtils
-        .unexpectedErrorResponse(deserializedResponse: dictionary, underlyingError: error)
+        .RPCResponseDecodingError(deserializedResponse: dictionary, underlyingError: failure)
     }
+  }
 
-    // Finally, we try to populate the response object with the JSON values.
-    do {
-      try response.setFields(dictionary: dictionary)
-    } catch {
-      throw AuthErrorUtils
-        .RPCResponseDecodingError(deserializedResponse: dictionary, underlyingError: error)
+  private func propagateError(_ error: Error?, dictionary: [String: AnyHashable],
+                              response: AuthRPCResponse?) throws {
+    guard let error else {
+      return
     }
-    // In case returnIDPCredential of a verifyAssertion request is set to
-    // @YES, the server may return a 200 with a response that may contain a
-    // server error.
-    if let verifyAssertionRequest = request as? VerifyAssertionRequest {
-      if verifyAssertionRequest.returnIDPCredential {
-        if let errorMessage = dictionary["errorMessage"] as? String {
-          if let clientError = Self.clientError(
-            withServerErrorMessage: errorMessage,
-            errorDictionary: dictionary,
-            response: response,
-            error: error
-          ) {
-            throw clientError
-          }
+
+    if let errorDictionary = dictionary["error"] as? [String: AnyHashable] {
+      if let errorMessage = errorDictionary["message"] as? String {
+        if let clientError = Self.clientError(
+          withServerErrorMessage: errorMessage,
+          errorDictionary: errorDictionary,
+          response: response,
+          error: error
+        ) {
+          throw clientError
         }
       }
+      // Not a message we know, return the message directly.
+      throw AuthErrorUtils.unexpectedErrorResponse(
+        deserializedResponse: errorDictionary,
+        underlyingError: error
+      )
     }
-    return response
+    // No error message at all, return the decoded response.
+    throw AuthErrorUtils
+      .unexpectedErrorResponse(deserializedResponse: dictionary, underlyingError: error)
   }
 
   private static func clientError(withServerErrorMessage serverErrorMessage: String,
                                   errorDictionary: [String: Any],
-                                  response: AuthRPCResponse,
+                                  response: AuthRPCResponse?,
                                   error: Error?) -> Error? {
     let split = serverErrorMessage.split(separator: ":")
     let shortErrorMessage = split.first?.trimmingCharacters(in: .whitespacesAndNewlines)
diff --git a/FirebaseAuth/Sources/Swift/Backend/AuthRPCResponse.swift b/FirebaseAuth/Sources/Swift/Backend/AuthRPCResponse.swift
index 0b7ea8a3a52..00d302e5775 100644
--- a/FirebaseAuth/Sources/Swift/Backend/AuthRPCResponse.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/AuthRPCResponse.swift
@@ -15,14 +15,11 @@
 import Foundation
 
 protocol AuthRPCResponse: Sendable {
-  /// Bare initializer for a response.
-  init()
-
-  /// Sets the response instance from the decoded JSON response.
+  /// Initializes the response instance from the decoded JSON response.
   /// - Parameter dictionary: The dictionary decoded from HTTP JSON response.
   /// - Parameter error: An out field for an error which occurred constructing the request.
   /// - Returns: Whether the operation was successful or not.
-  mutating func setFields(dictionary: [String: AnyHashable]) throws
+  init(dictionary: [String: AnyHashable]) throws
 
   /// This optional method allows response classes to create client errors given a short error
   /// message and a detail error message from the server.
diff --git a/FirebaseAuth/Sources/Swift/Backend/IdentityToolkitRequest.swift b/FirebaseAuth/Sources/Swift/Backend/IdentityToolkitRequest.swift
index 3ee424459a5..3a5d5a3b18a 100644
--- a/FirebaseAuth/Sources/Swift/Backend/IdentityToolkitRequest.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/IdentityToolkitRequest.swift
@@ -19,7 +19,15 @@ private let kHttpProtocol = "http:"
 
 private let kEmulatorHostAndPrefixFormat = "%@/%@"
 
-private var gAPIHost = "www.googleapis.com"
+#if compiler(>=6)
+  /// Host for server API calls. This should be changed via
+  /// `IdentityToolkitRequest.setHost(_ host:)` for testing purposes only.
+  private nonisolated(unsafe) var gAPIHost = "www.googleapis.com"
+#else
+  /// Host for server API calls. This should be changed via
+  /// `IdentityToolkitRequest.setHost(_ host:)` for testing purposes only.
+  private var gAPIHost = "www.googleapis.com"
+#endif // compiler(>=6)
 
 private let kFirebaseAuthAPIHost = "www.googleapis.com"
 private let kIdentityPlatformAPIHost = "identitytoolkit.googleapis.com"
diff --git a/FirebaseAuth/Sources/Swift/Backend/RPC/CreateAuthURIResponse.swift b/FirebaseAuth/Sources/Swift/Backend/RPC/CreateAuthURIResponse.swift
index 019a92f4b90..66b1ad95023 100644
--- a/FirebaseAuth/Sources/Swift/Backend/RPC/CreateAuthURIResponse.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/RPC/CreateAuthURIResponse.swift
@@ -35,7 +35,7 @@ struct CreateAuthURIResponse: AuthRPCResponse {
   /// A list of sign-in methods available for the passed identifier.
   var signinMethods: [String] = []
 
-  mutating func setFields(dictionary: [String: AnyHashable]) throws {
+  init(dictionary: [String: AnyHashable]) throws {
     providerID = dictionary["providerId"] as? String
     authURI = dictionary["authUri"] as? String
     registered = dictionary["registered"] as? Bool ?? false
diff --git a/FirebaseAuth/Sources/Swift/Backend/RPC/DeleteAccountResponse.swift b/FirebaseAuth/Sources/Swift/Backend/RPC/DeleteAccountResponse.swift
index 4b6802dafb3..d3a34371caa 100644
--- a/FirebaseAuth/Sources/Swift/Backend/RPC/DeleteAccountResponse.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/RPC/DeleteAccountResponse.swift
@@ -18,5 +18,5 @@ import Foundation
 ///
 /// See https://developers.google.com/identity/toolkit/web/reference/relyingparty/deleteAccount
 struct DeleteAccountResponse: AuthRPCResponse {
-  mutating func setFields(dictionary: [String: AnyHashable]) throws {}
+  init(dictionary: [String: AnyHashable]) throws {}
 }
diff --git a/FirebaseAuth/Sources/Swift/Backend/RPC/EmailLinkSignInResponse.swift b/FirebaseAuth/Sources/Swift/Backend/RPC/EmailLinkSignInResponse.swift
index 608c38237cc..0fb80a8f9c2 100644
--- a/FirebaseAuth/Sources/Swift/Backend/RPC/EmailLinkSignInResponse.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/RPC/EmailLinkSignInResponse.swift
@@ -40,7 +40,7 @@ struct EmailLinkSignInResponse: AuthRPCResponse, AuthMFAResponse {
   /// Info on which multi-factor authentication providers are enabled.
   private(set) var mfaInfo: [AuthProtoMFAEnrollment]?
 
-  mutating func setFields(dictionary: [String: AnyHashable]) throws {
+  init(dictionary: [String: AnyHashable]) throws {
     email = dictionary["email"] as? String
     idToken = dictionary["idToken"] as? String
     isNewUser = dictionary["isNewUser"] as? Bool ?? false
diff --git a/FirebaseAuth/Sources/Swift/Backend/RPC/GetAccountInfoResponse.swift b/FirebaseAuth/Sources/Swift/Backend/RPC/GetAccountInfoResponse.swift
index e0f9c463959..4fb5795bcd5 100644
--- a/FirebaseAuth/Sources/Swift/Backend/RPC/GetAccountInfoResponse.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/RPC/GetAccountInfoResponse.swift
@@ -139,7 +139,7 @@ struct GetAccountInfoResponse: AuthRPCResponse {
   /// The requested users' profiles.
   var users: [Self.User]?
 
-  mutating func setFields(dictionary: [String: AnyHashable]) throws {
+  init(dictionary: [String: AnyHashable]) throws {
     guard let usersData = dictionary["users"] as? [[String: AnyHashable]] else {
       throw AuthErrorUtils.unexpectedResponse(deserializedResponse: dictionary)
     }
diff --git a/FirebaseAuth/Sources/Swift/Backend/RPC/GetOOBConfirmationCodeResponse.swift b/FirebaseAuth/Sources/Swift/Backend/RPC/GetOOBConfirmationCodeResponse.swift
index 91721fd659e..dcfba9d5212 100644
--- a/FirebaseAuth/Sources/Swift/Backend/RPC/GetOOBConfirmationCodeResponse.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/RPC/GetOOBConfirmationCodeResponse.swift
@@ -19,7 +19,7 @@ private let kOOBCodeKey = "oobCode"
 struct GetOOBConfirmationCodeResponse: AuthRPCResponse {
   var OOBCode: String?
 
-  mutating func setFields(dictionary: [String: AnyHashable]) throws {
+  init(dictionary: [String: AnyHashable]) throws {
     OOBCode = dictionary[kOOBCodeKey] as? String
   }
 }
diff --git a/FirebaseAuth/Sources/Swift/Backend/RPC/GetProjectConfigResponse.swift b/FirebaseAuth/Sources/Swift/Backend/RPC/GetProjectConfigResponse.swift
index b9fb18771b7..65091a46c7e 100644
--- a/FirebaseAuth/Sources/Swift/Backend/RPC/GetProjectConfigResponse.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/RPC/GetProjectConfigResponse.swift
@@ -19,7 +19,7 @@ struct GetProjectConfigResponse: AuthRPCResponse {
 
   var authorizedDomains: [String]?
 
-  mutating func setFields(dictionary: [String: AnyHashable]) throws {
+  init(dictionary: [String: AnyHashable]) throws {
     projectID = dictionary["projectId"] as? String
     if let authorizedDomains = dictionary["authorizedDomains"] as? String,
        let data = authorizedDomains.data(using: .utf8) {
diff --git a/FirebaseAuth/Sources/Swift/Backend/RPC/GetRecaptchaConfigResponse.swift b/FirebaseAuth/Sources/Swift/Backend/RPC/GetRecaptchaConfigResponse.swift
index b62bd84a695..327ff3751a2 100644
--- a/FirebaseAuth/Sources/Swift/Backend/RPC/GetRecaptchaConfigResponse.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/RPC/GetRecaptchaConfigResponse.swift
@@ -18,7 +18,7 @@ struct GetRecaptchaConfigResponse: AuthRPCResponse {
   private(set) var recaptchaKey: String?
   private(set) var enforcementState: [[String: String]]?
 
-  mutating func setFields(dictionary: [String: AnyHashable]) throws {
+  init(dictionary: [String: AnyHashable]) throws {
     recaptchaKey = dictionary["recaptchaKey"] as? String
     enforcementState = dictionary["recaptchaEnforcementState"] as? [[String: String]]
   }
diff --git a/FirebaseAuth/Sources/Swift/Backend/RPC/MultiFactor/Enroll/FinalizeMFAEnrollmentResponse.swift b/FirebaseAuth/Sources/Swift/Backend/RPC/MultiFactor/Enroll/FinalizeMFAEnrollmentResponse.swift
index bdd3ce89d31..595e3b45952 100644
--- a/FirebaseAuth/Sources/Swift/Backend/RPC/MultiFactor/Enroll/FinalizeMFAEnrollmentResponse.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/RPC/MultiFactor/Enroll/FinalizeMFAEnrollmentResponse.swift
@@ -21,7 +21,7 @@ struct FinalizeMFAEnrollmentResponse: AuthRPCResponse {
   private(set) var phoneSessionInfo: AuthProtoFinalizeMFAPhoneResponseInfo?
   private(set) var totpSessionInfo: AuthProtoFinalizeMFATOTPEnrollmentResponseInfo?
 
-  mutating func setFields(dictionary: [String: AnyHashable]) throws {
+  init(dictionary: [String: AnyHashable]) throws {
     idToken = dictionary["idToken"] as? String
     refreshToken = dictionary["refreshToken"] as? String
 
diff --git a/FirebaseAuth/Sources/Swift/Backend/RPC/MultiFactor/Enroll/StartMFAEnrollmentResponse.swift b/FirebaseAuth/Sources/Swift/Backend/RPC/MultiFactor/Enroll/StartMFAEnrollmentResponse.swift
index dadbb9a15be..7c91b54227c 100644
--- a/FirebaseAuth/Sources/Swift/Backend/RPC/MultiFactor/Enroll/StartMFAEnrollmentResponse.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/RPC/MultiFactor/Enroll/StartMFAEnrollmentResponse.swift
@@ -19,7 +19,7 @@ struct StartMFAEnrollmentResponse: AuthRPCResponse {
   private(set) var phoneSessionInfo: AuthProtoStartMFAPhoneResponseInfo?
   private(set) var totpSessionInfo: AuthProtoStartMFATOTPEnrollmentResponseInfo?
 
-  mutating func setFields(dictionary: [String: AnyHashable]) throws {
+  init(dictionary: [String: AnyHashable]) throws {
     if let data = dictionary["phoneSessionInfo"] as? [String: AnyHashable] {
       phoneSessionInfo = AuthProtoStartMFAPhoneResponseInfo(dictionary: data)
     } else if let data = dictionary["totpSessionInfo"] as? [String: AnyHashable] {
diff --git a/FirebaseAuth/Sources/Swift/Backend/RPC/MultiFactor/SignIn/FinalizeMFASignInResponse.swift b/FirebaseAuth/Sources/Swift/Backend/RPC/MultiFactor/SignIn/FinalizeMFASignInResponse.swift
index 032dab3ff86..850a969e6cd 100644
--- a/FirebaseAuth/Sources/Swift/Backend/RPC/MultiFactor/SignIn/FinalizeMFASignInResponse.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/RPC/MultiFactor/SignIn/FinalizeMFASignInResponse.swift
@@ -19,7 +19,7 @@ struct FinalizeMFASignInResponse: AuthRPCResponse {
   var IDToken: String?
   var refreshToken: String?
 
-  mutating func setFields(dictionary: [String: AnyHashable]) throws {
+  init(dictionary: [String: AnyHashable]) throws {
     IDToken = dictionary["idToken"] as? String
     refreshToken = dictionary["refreshToken"] as? String
   }
diff --git a/FirebaseAuth/Sources/Swift/Backend/RPC/MultiFactor/SignIn/StartMFASignInResponse.swift b/FirebaseAuth/Sources/Swift/Backend/RPC/MultiFactor/SignIn/StartMFASignInResponse.swift
index cc597172010..291821c58f9 100644
--- a/FirebaseAuth/Sources/Swift/Backend/RPC/MultiFactor/SignIn/StartMFASignInResponse.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/RPC/MultiFactor/SignIn/StartMFASignInResponse.swift
@@ -18,7 +18,7 @@ import Foundation
 struct StartMFASignInResponse: AuthRPCResponse {
   var responseInfo: AuthProtoStartMFAPhoneResponseInfo?
 
-  mutating func setFields(dictionary: [String: AnyHashable]) throws {
+  init(dictionary: [String: AnyHashable]) throws {
     if let data = dictionary["phoneResponseInfo"] as? [String: AnyHashable] {
       responseInfo = AuthProtoStartMFAPhoneResponseInfo(dictionary: data)
     } else {
diff --git a/FirebaseAuth/Sources/Swift/Backend/RPC/MultiFactor/Unenroll/WithdrawMFAResponse.swift b/FirebaseAuth/Sources/Swift/Backend/RPC/MultiFactor/Unenroll/WithdrawMFAResponse.swift
index 4744a6965ee..27bcd0d32e4 100644
--- a/FirebaseAuth/Sources/Swift/Backend/RPC/MultiFactor/Unenroll/WithdrawMFAResponse.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/RPC/MultiFactor/Unenroll/WithdrawMFAResponse.swift
@@ -18,7 +18,7 @@ struct WithdrawMFAResponse: AuthRPCResponse {
   var idToken: String?
   var refreshToken: String?
 
-  mutating func setFields(dictionary: [String: AnyHashable]) throws {
+  init(dictionary: [String: AnyHashable]) throws {
     idToken = dictionary["idToken"] as? String
     refreshToken = dictionary["refreshToken"] as? String
   }
diff --git a/FirebaseAuth/Sources/Swift/Backend/RPC/ResetPasswordResponse.swift b/FirebaseAuth/Sources/Swift/Backend/RPC/ResetPasswordResponse.swift
index 22cb703e5ad..1744dfc34cf 100644
--- a/FirebaseAuth/Sources/Swift/Backend/RPC/ResetPasswordResponse.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/RPC/ResetPasswordResponse.swift
@@ -34,7 +34,7 @@ struct ResetPasswordResponse: AuthRPCResponse {
   /// The type of request as returned by the backend.
   var requestType: String?
 
-  mutating func setFields(dictionary: [String: AnyHashable]) throws {
+  init(dictionary: [String: AnyHashable]) throws {
     email = dictionary["email"] as? String
     requestType = dictionary["requestType"] as? String
     verifiedEmail = dictionary["newEmail"] as? String
diff --git a/FirebaseAuth/Sources/Swift/Backend/RPC/RevokeTokenResponse.swift b/FirebaseAuth/Sources/Swift/Backend/RPC/RevokeTokenResponse.swift
index 7e6bf0e7378..900959ccbe1 100644
--- a/FirebaseAuth/Sources/Swift/Backend/RPC/RevokeTokenResponse.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/RPC/RevokeTokenResponse.swift
@@ -15,7 +15,7 @@
 import Foundation
 
 struct RevokeTokenResponse: AuthRPCResponse {
-  mutating func setFields(dictionary: [String: AnyHashable]) throws {
+  init(dictionary: [String: AnyHashable]) throws {
     // Nothing to set or throw.
   }
 }
diff --git a/FirebaseAuth/Sources/Swift/Backend/RPC/SecureTokenRequest.swift b/FirebaseAuth/Sources/Swift/Backend/RPC/SecureTokenRequest.swift
index c07d60c7a60..d11275dcf29 100644
--- a/FirebaseAuth/Sources/Swift/Backend/RPC/SecureTokenRequest.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/RPC/SecureTokenRequest.swift
@@ -54,12 +54,19 @@ private let kRefreshTokenKey = "refreshToken"
 /// The key for the "code" parameter in the request.
 private let kCodeKey = "code"
 
-/// Host for server API calls.
-private var gAPIHost = "securetoken.googleapis.com"
+#if compiler(>=6)
+  /// Host for server API calls. This should be changed via
+  /// `SecureTokenRequest.setHost(_ host:)` for testing purposes only.
+  private nonisolated(unsafe) var gAPIHost = "securetoken.googleapis.com"
+#else
+  /// Host for server API calls. This should be changed via
+  /// `SecureTokenRequest.setHost(_ host:)` for testing purposes only.
+  private var gAPIHost = "securetoken.googleapis.com"
+#endif // compiler(>=6)
 
 /// Represents the parameters for the token endpoint.
 @available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
-struct SecureTokenRequest: AuthRPCRequest {
+class SecureTokenRequest: AuthRPCRequest {
   typealias Response = SecureTokenResponse
 
   /// The type of grant requested.
diff --git a/FirebaseAuth/Sources/Swift/Backend/RPC/SecureTokenResponse.swift b/FirebaseAuth/Sources/Swift/Backend/RPC/SecureTokenResponse.swift
index 86291a60015..44409ba92d4 100644
--- a/FirebaseAuth/Sources/Swift/Backend/RPC/SecureTokenResponse.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/RPC/SecureTokenResponse.swift
@@ -37,7 +37,7 @@ struct SecureTokenResponse: AuthRPCResponse {
 
   var expectedKind: String? { nil }
 
-  mutating func setFields(dictionary: [String: AnyHashable]) throws {
+  init(dictionary: [String: AnyHashable]) throws {
     refreshToken = dictionary[kRefreshTokenKey] as? String
     self.accessToken = dictionary[kAccessTokenKey] as? String
     idToken = dictionary[kIDTokenKey] as? String
diff --git a/FirebaseAuth/Sources/Swift/Backend/RPC/SendVerificationTokenResponse.swift b/FirebaseAuth/Sources/Swift/Backend/RPC/SendVerificationTokenResponse.swift
index f9e6872cfcb..7b1815c5925 100644
--- a/FirebaseAuth/Sources/Swift/Backend/RPC/SendVerificationTokenResponse.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/RPC/SendVerificationTokenResponse.swift
@@ -17,7 +17,7 @@ import Foundation
 struct SendVerificationCodeResponse: AuthRPCResponse {
   var verificationID: String?
 
-  mutating func setFields(dictionary: [String: AnyHashable]) throws {
+  init(dictionary: [String: AnyHashable]) throws {
     verificationID = dictionary["sessionInfo"] as? String
   }
 }
diff --git a/FirebaseAuth/Sources/Swift/Backend/RPC/SetAccountInfoResponse.swift b/FirebaseAuth/Sources/Swift/Backend/RPC/SetAccountInfoResponse.swift
index c1b932b83c2..0a036d95195 100644
--- a/FirebaseAuth/Sources/Swift/Backend/RPC/SetAccountInfoResponse.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/RPC/SetAccountInfoResponse.swift
@@ -60,7 +60,7 @@ struct SetAccountInfoResponse: AuthRPCResponse {
   /// The refresh token from Secure Token Service.
   var refreshToken: String?
 
-  mutating func setFields(dictionary: [String: AnyHashable]) throws {
+  init(dictionary: [String: AnyHashable]) throws {
     email = dictionary["email"] as? String
     displayName = dictionary["displayName"] as? String
     idToken = dictionary["idToken"] as? String
diff --git a/FirebaseAuth/Sources/Swift/Backend/RPC/SignInWithGameCenterResponse.swift b/FirebaseAuth/Sources/Swift/Backend/RPC/SignInWithGameCenterResponse.swift
index d291384ff49..cc81610b17b 100644
--- a/FirebaseAuth/Sources/Swift/Backend/RPC/SignInWithGameCenterResponse.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/RPC/SignInWithGameCenterResponse.swift
@@ -25,7 +25,7 @@ struct SignInWithGameCenterResponse: AuthRPCResponse {
   var isNewUser: Bool = false
   var displayName: String?
 
-  mutating func setFields(dictionary: [String: AnyHashable]) throws {
+  init(dictionary: [String: AnyHashable]) throws {
     idToken = dictionary["idToken"] as? String
     refreshToken = dictionary["refreshToken"] as? String
     localID = dictionary["localId"] as? String
diff --git a/FirebaseAuth/Sources/Swift/Backend/RPC/SignUpNewUserResponse.swift b/FirebaseAuth/Sources/Swift/Backend/RPC/SignUpNewUserResponse.swift
index 7b25c6a6f8c..21f359b0f1a 100644
--- a/FirebaseAuth/Sources/Swift/Backend/RPC/SignUpNewUserResponse.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/RPC/SignUpNewUserResponse.swift
@@ -26,7 +26,7 @@ struct SignUpNewUserResponse: AuthRPCResponse {
   /// The refresh token from Secure Token Service.
   var refreshToken: String?
 
-  mutating func setFields(dictionary: [String: AnyHashable]) throws {
+  init(dictionary: [String: AnyHashable]) throws {
     idToken = dictionary["idToken"] as? String
     if let approximateExpirationDate = dictionary["expiresIn"] as? String {
       self
diff --git a/FirebaseAuth/Sources/Swift/Backend/RPC/VerifyAssertionResponse.swift b/FirebaseAuth/Sources/Swift/Backend/RPC/VerifyAssertionResponse.swift
index c031aa22c43..9caa9d38e35 100644
--- a/FirebaseAuth/Sources/Swift/Backend/RPC/VerifyAssertionResponse.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/RPC/VerifyAssertionResponse.swift
@@ -132,7 +132,7 @@ struct VerifyAssertionResponse: AuthRPCResponse, AuthMFAResponse {
 
   private(set) var mfaInfo: [AuthProtoMFAEnrollment]?
 
-  mutating func setFields(dictionary: [String: AnyHashable]) throws {
+  init(dictionary: [String: AnyHashable]) throws {
     federatedID = dictionary["federatedId"] as? String
     providerID = dictionary["providerId"] as? String
     localID = dictionary["localId"] as? String
diff --git a/FirebaseAuth/Sources/Swift/Backend/RPC/VerifyCustomTokenResponse.swift b/FirebaseAuth/Sources/Swift/Backend/RPC/VerifyCustomTokenResponse.swift
index 5c66bf6ba74..9cf1ec0924f 100644
--- a/FirebaseAuth/Sources/Swift/Backend/RPC/VerifyCustomTokenResponse.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/RPC/VerifyCustomTokenResponse.swift
@@ -30,7 +30,7 @@ struct VerifyCustomTokenResponse: AuthRPCResponse {
   /// Flag indicating that the user signing in is a new user and not a returning user.
   var isNewUser: Bool = false
 
-  mutating func setFields(dictionary: [String: AnyHashable]) throws {
+  init(dictionary: [String: AnyHashable]) throws {
     idToken = dictionary["idToken"] as? String
     if let dateString = dictionary["expiresIn"] as? NSString {
       approximateExpirationDate = Date(timeIntervalSinceNow: dateString.doubleValue)
diff --git a/FirebaseAuth/Sources/Swift/Backend/RPC/VerifyPasswordResponse.swift b/FirebaseAuth/Sources/Swift/Backend/RPC/VerifyPasswordResponse.swift
index ba93ac1e0a5..22a3d87e958 100644
--- a/FirebaseAuth/Sources/Swift/Backend/RPC/VerifyPasswordResponse.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/RPC/VerifyPasswordResponse.swift
@@ -51,7 +51,7 @@ struct VerifyPasswordResponse: AuthRPCResponse, AuthMFAResponse {
 
   private(set) var mfaInfo: [AuthProtoMFAEnrollment]?
 
-  mutating func setFields(dictionary: [String: AnyHashable]) throws {
+  init(dictionary: [String: AnyHashable]) throws {
     localID = dictionary["localId"] as? String
     email = dictionary["email"] as? String
     displayName = dictionary["displayName"] as? String
diff --git a/FirebaseAuth/Sources/Swift/Backend/RPC/VerifyPhoneNumberResponse.swift b/FirebaseAuth/Sources/Swift/Backend/RPC/VerifyPhoneNumberResponse.swift
index b5efb964c73..a187824b7dd 100644
--- a/FirebaseAuth/Sources/Swift/Backend/RPC/VerifyPhoneNumberResponse.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/RPC/VerifyPhoneNumberResponse.swift
@@ -43,7 +43,7 @@ struct VerifyPhoneNumberResponse: AuthRPCResponse {
     nil
   }
 
-  mutating func setFields(dictionary: [String: AnyHashable]) throws {
+  init(dictionary: [String: AnyHashable]) throws {
     idToken = dictionary["idToken"] as? String
     refreshToken = dictionary["refreshToken"] as? String
     isNewUser = (dictionary["isNewUser"] as? Bool) ?? false
diff --git a/FirebaseAuth/Sources/Swift/Backend/VerifyClientResponse.swift b/FirebaseAuth/Sources/Swift/Backend/VerifyClientResponse.swift
index 683ed33a01f..a468197948f 100644
--- a/FirebaseAuth/Sources/Swift/Backend/VerifyClientResponse.swift
+++ b/FirebaseAuth/Sources/Swift/Backend/VerifyClientResponse.swift
@@ -15,15 +15,13 @@
 import Foundation
 
 struct VerifyClientResponse: AuthRPCResponse {
-  init() {}
-
   /// Receipt that the APNS token was successfully validated with APNS.
   private(set) var receipt: String?
 
   /// The date after which delivery of the silent push notification is considered to have failed.
   private(set) var suggestedTimeOutDate: Date?
 
-  mutating func setFields(dictionary: [String: AnyHashable]) throws {
+  init(dictionary: [String: AnyHashable]) throws {
     receipt = dictionary["receipt"] as? String
     let suggestedTimeout = dictionary["suggestedTimeout"]
     if let string = suggestedTimeout as? String,
diff --git a/FirebaseAuth/Sources/Swift/MultiFactor/MultiFactor.swift b/FirebaseAuth/Sources/Swift/MultiFactor/MultiFactor.swift
index f3dd5b26981..c60f353e362 100644
--- a/FirebaseAuth/Sources/Swift/MultiFactor/MultiFactor.swift
+++ b/FirebaseAuth/Sources/Swift/MultiFactor/MultiFactor.swift
@@ -88,7 +88,7 @@ import Foundation
                                                        .requestConfiguration)
           Task {
             do {
-              let response = try await AuthBackend.call(with: request)
+              let response = try await auth.backend.call(with: request)
               do {
                 let user = try await auth.completeSignIn(withAccessToken: response.idToken,
                                                          accessTokenExpirationDate: nil,
@@ -139,7 +139,7 @@ import Foundation
 
         Task {
           do {
-            let response = try await AuthBackend.call(with: request)
+            let response = try await auth.backend.call(with: request)
             do {
               let user = try await auth.completeSignIn(withAccessToken: response.idToken,
                                                        accessTokenExpirationDate: nil,
@@ -217,7 +217,7 @@ import Foundation
                                        requestConfiguration: user.requestConfiguration)
       Task {
         do {
-          let response = try await AuthBackend.call(with: request)
+          let response = try await auth.backend.call(with: request)
           do {
             let user = try await auth.completeSignIn(withAccessToken: response.idToken,
                                                      accessTokenExpirationDate: nil,
diff --git a/FirebaseAuth/Sources/Swift/MultiFactor/MultiFactorResolver.swift b/FirebaseAuth/Sources/Swift/MultiFactor/MultiFactorResolver.swift
index 64b8bdda693..366ccc02023 100644
--- a/FirebaseAuth/Sources/Swift/MultiFactor/MultiFactorResolver.swift
+++ b/FirebaseAuth/Sources/Swift/MultiFactor/MultiFactorResolver.swift
@@ -72,7 +72,7 @@ import Foundation
       )
       Task {
         do {
-          let response = try await AuthBackend.call(with: request)
+          let response = try await self.auth.backend.call(with: request)
           let user = try await self.auth.completeSignIn(withAccessToken: response.idToken,
                                                         accessTokenExpirationDate: nil,
                                                         refreshToken: response.refreshToken,
diff --git a/FirebaseAuth/Sources/Swift/MultiFactor/TOTP/TOTPMultiFactorGenerator.swift b/FirebaseAuth/Sources/Swift/MultiFactor/TOTP/TOTPMultiFactorGenerator.swift
index 4fc574caedb..bf3b07634ca 100644
--- a/FirebaseAuth/Sources/Swift/MultiFactor/TOTP/TOTPMultiFactorGenerator.swift
+++ b/FirebaseAuth/Sources/Swift/MultiFactor/TOTP/TOTPMultiFactorGenerator.swift
@@ -31,8 +31,7 @@ import Foundation
     @objc(generateSecretWithMultiFactorSession:completion:)
     open class func generateSecret(with session: MultiFactorSession,
                                    completion: @escaping (TOTPSecret?, Error?) -> Void) {
-      guard let currentUser = session.currentUser,
-            let requestConfiguration = currentUser.auth?.requestConfiguration else {
+      guard let currentUser = session.currentUser, let auth = currentUser.auth else {
         let error = AuthErrorUtils.error(code: AuthErrorCode.internalError,
                                          userInfo: [NSLocalizedDescriptionKey:
                                            "Invalid ID token."])
@@ -42,10 +41,10 @@ import Foundation
       let totpEnrollmentInfo = AuthProtoStartMFATOTPEnrollmentRequestInfo()
       let request = StartMFAEnrollmentRequest(idToken: session.idToken,
                                               totpEnrollmentInfo: totpEnrollmentInfo,
-                                              requestConfiguration: requestConfiguration)
+                                              requestConfiguration: auth.requestConfiguration)
       Task {
         do {
-          let response = try await AuthBackend.call(with: request)
+          let response = try await auth.backend.call(with: request)
           if let totpSessionInfo = response.totpSessionInfo {
             let secret = TOTPSecret(secretKey: totpSessionInfo.sharedSecretKey,
                                     hashingAlgorithm: totpSessionInfo.hashingAlgorithm,
diff --git a/FirebaseAuth/Sources/Swift/SystemService/SecureTokenService.swift b/FirebaseAuth/Sources/Swift/SystemService/SecureTokenService.swift
index dd9e6dbde13..6bdee4c395a 100644
--- a/FirebaseAuth/Sources/Swift/SystemService/SecureTokenService.swift
+++ b/FirebaseAuth/Sources/Swift/SystemService/SecureTokenService.swift
@@ -25,12 +25,13 @@ actor SecureTokenServiceInternal {
   /// - Parameter forceRefresh: Forces the token to be refreshed.
   /// - Returns : A tuple with the token and flag of whether it was updated.
   func fetchAccessToken(forcingRefresh forceRefresh: Bool,
-                        service: SecureTokenService) async throws -> (String?, Bool) {
+                        service: SecureTokenService,
+                        backend: AuthBackend) async throws -> (String?, Bool) {
     if !forceRefresh, hasValidAccessToken(service: service) {
       return (service.accessToken, false)
     } else {
       AuthLog.logDebug(code: "I-AUT000017", message: "Fetching new token from backend.")
-      return try await requestAccessToken(retryIfExpired: true, service: service)
+      return try await requestAccessToken(retryIfExpired: true, service: service, backend: backend)
     }
   }
 
@@ -41,7 +42,8 @@ actor SecureTokenServiceInternal {
   ///
   /// - Returns: Token and Bool indicating if update occurred.
   private func requestAccessToken(retryIfExpired: Bool,
-                                  service: SecureTokenService) async throws -> (String?, Bool) {
+                                  service: SecureTokenService,
+                                  backend: AuthBackend) async throws -> (String?, Bool) {
     // TODO: This was a crash in ObjC SDK, should it callback with an error?
     guard let refreshToken = service.refreshToken,
           let requestConfiguration = service.requestConfiguration else {
@@ -50,7 +52,7 @@ actor SecureTokenServiceInternal {
 
     let request = SecureTokenRequest.refreshRequest(refreshToken: refreshToken,
                                                     requestConfiguration: requestConfiguration)
-    let response = try await AuthBackend.call(with: request)
+    let response = try await backend.call(with: request)
     var tokenUpdated = false
     if let newAccessToken = response.accessToken,
        newAccessToken.count > 0,
@@ -67,7 +69,11 @@ actor SecureTokenServiceInternal {
           if expirationDate.timeIntervalSinceNow <= kFiveMinutes {
             // We only retry once, to avoid an infinite loop in the case that an end-user has
             // their local time skewed by over an hour.
-            return try await requestAccessToken(retryIfExpired: false, service: service)
+            return try await requestAccessToken(
+              retryIfExpired: false,
+              service: service,
+              backend: backend
+            )
           }
         }
       }
@@ -152,8 +158,10 @@ class SecureTokenService: NSObject, NSSecureCoding {
   ///    Invoked asynchronously on the auth global work queue in the future.
   /// - Parameter forceRefresh: Forces the token to be refreshed.
   /// - Returns : A tuple with the token and flag of whether it was updated.
-  func fetchAccessToken(forcingRefresh forceRefresh: Bool) async throws -> (String?, Bool) {
-    return try await internalService.fetchAccessToken(forcingRefresh: forceRefresh, service: self)
+  func fetchAccessToken(forcingRefresh forceRefresh: Bool,
+                        backend: AuthBackend) async throws -> (String?, Bool) {
+    return try await internalService
+      .fetchAccessToken(forcingRefresh: forceRefresh, service: self, backend: backend)
   }
 
   // MARK: NSSecureCoding
diff --git a/FirebaseAuth/Sources/Swift/User/User.swift b/FirebaseAuth/Sources/Swift/User/User.swift
index 3371520bdf8..fccd96ab088 100644
--- a/FirebaseAuth/Sources/Swift/User/User.swift
+++ b/FirebaseAuth/Sources/Swift/User/User.swift
@@ -49,6 +49,9 @@ extension User: NSSecureCoding {}
 
   var providerDataRaw: [String: UserInfoImpl]
 
+  /// The backend service for the given instance.
+  private(set) var backend: AuthBackend
+
   /// Metadata associated with the Firebase user in question.
   @objc public private(set) var metadata: UserMetadata
 
@@ -583,7 +586,7 @@ extension User: NSSecureCoding {}
   open func getIDTokenResult(forcingRefresh: Bool,
                              completion: ((AuthTokenResult?, Error?) -> Void)?) {
     kAuthGlobalWorkQueue.async {
-      self.internalGetToken(forceRefresh: forcingRefresh) { token, error in
+      self.internalGetToken(forceRefresh: forcingRefresh, backend: self.backend) { token, error in
         var tokenResult: AuthTokenResult?
         if let token {
           do {
@@ -866,7 +869,7 @@ extension User: NSSecureCoding {}
   open func sendEmailVerification(with actionCodeSettings: ActionCodeSettings? = nil,
                                   completion: ((Error?) -> Void)? = nil) {
     kAuthGlobalWorkQueue.async {
-      self.internalGetToken { accessToken, error in
+      self.internalGetToken(backend: self.backend) { accessToken, error in
         if let error {
           User.callInMainThreadWithError(callback: completion, error: error)
           return
@@ -884,7 +887,7 @@ extension User: NSSecureCoding {}
         )
         Task {
           do {
-            let _ = try await AuthBackend.call(with: request)
+            let _ = try await self.backend.call(with: request)
             User.callInMainThreadWithError(callback: completion, error: nil)
           } catch {
             self.signOutIfTokenIsInvalid(withError: error)
@@ -931,7 +934,7 @@ extension User: NSSecureCoding {}
   /// is complete, or fails. Invoked asynchronously on the main thread in the future.
   @objc open func delete(completion: ((Error?) -> Void)? = nil) {
     kAuthGlobalWorkQueue.async {
-      self.internalGetToken { accessToken, error in
+      self.internalGetToken(backend: self.backend) { accessToken, error in
         if let error {
           User.callInMainThreadWithError(callback: completion, error: error)
           return
@@ -946,7 +949,7 @@ extension User: NSSecureCoding {}
                                            requestConfiguration: requestConfiguration)
         Task {
           do {
-            let _ = try await AuthBackend.call(with: request)
+            let _ = try await self.backend.call(with: request)
             try self.auth?.signOutByForce(withUserID: self.uid)
             User.callInMainThreadWithError(callback: completion, error: nil)
           } catch {
@@ -996,7 +999,7 @@ extension User: NSSecureCoding {}
                                         actionCodeSettings: ActionCodeSettings? = nil,
                                         completion: ((Error?) -> Void)? = nil) {
     kAuthGlobalWorkQueue.async {
-      self.internalGetToken { accessToken, error in
+      self.internalGetToken(backend: self.backend) { accessToken, error in
         if let error {
           User.callInMainThreadWithError(callback: completion, error: error)
           return
@@ -1015,7 +1018,7 @@ extension User: NSSecureCoding {}
         )
         Task {
           do {
-            let _ = try await AuthBackend.call(with: request)
+            let _ = try await self.backend.call(with: request)
             User.callInMainThreadWithError(callback: completion, error: nil)
           } catch {
             User.callInMainThreadWithError(callback: completion, error: error)
@@ -1054,7 +1057,8 @@ extension User: NSSecureCoding {}
     return tokenService.accessTokenExpirationDate
   }
 
-  init(withTokenService tokenService: SecureTokenService) {
+  init(withTokenService tokenService: SecureTokenService, backend: AuthBackend) {
+    self.backend = backend
     providerDataRaw = [:]
     userProfileUpdate = UserProfileUpdate()
     self.tokenService = tokenService
@@ -1083,16 +1087,16 @@ extension User: NSSecureCoding {}
                                           accessToken: accessToken,
                                           accessTokenExpirationDate: accessTokenExpirationDate,
                                           refreshToken: refreshToken)
-    let user = User(withTokenService: tokenService)
+    let user = User(withTokenService: tokenService, backend: auth.backend)
     user.auth = auth
     user.tenantID = auth.tenantID
     user.requestConfiguration = auth.requestConfiguration
-    let accessToken2 = try await user.internalGetTokenAsync()
+    let accessToken2 = try await user.internalGetTokenAsync(backend: user.backend)
     let getAccountInfoRequest = GetAccountInfoRequest(
       accessToken: accessToken2,
       requestConfiguration: user.requestConfiguration
     )
-    let response = try await AuthBackend.call(with: getAccountInfoRequest)
+    let response = try await auth.backend.call(with: getAccountInfoRequest)
     user.isAnonymous = anonymous
     user.update(withGetAccountInfoResponse: response)
     return user
@@ -1137,12 +1141,13 @@ extension User: NSSecureCoding {}
   /// A weak reference to an `Auth` instance associated with this instance.
   weak var auth: Auth? {
     set {
-      _auth = newValue
-      guard let requestConfiguration = auth?.requestConfiguration else {
-        fatalError("Firebase Auth Internal Error: nil requestConfiguration when initializing User")
+      guard let newValue else {
+        fatalError("Firebase Auth Internal Error: Set user's auth property with non-nil instance.")
       }
+      _auth = newValue
+      requestConfiguration = newValue.requestConfiguration
       tokenService.requestConfiguration = requestConfiguration
-      self.requestConfiguration = requestConfiguration
+      backend = newValue.backend
     }
     get { return _auth }
   }
@@ -1173,12 +1178,12 @@ extension User: NSSecureCoding {}
           // The list of providers need to be updated for the newly added email-password provider.
           Task {
             do {
-              let accessToken = try await self.internalGetTokenAsync()
+              let accessToken = try await self.internalGetTokenAsync(backend: self.backend)
               if let requestConfiguration = self.auth?.requestConfiguration {
                 let getAccountInfoRequest = GetAccountInfoRequest(accessToken: accessToken,
                                                                   requestConfiguration: requestConfiguration)
                 do {
-                  let accountInfoResponse = try await AuthBackend.call(with: getAccountInfoRequest)
+                  let accountInfoResponse = try await self.backend.call(with: getAccountInfoRequest)
                   if let users = accountInfoResponse.users {
                     for userAccountInfo in users {
                       // Set the account to non-anonymous if there are any providers, even if
@@ -1313,7 +1318,7 @@ extension User: NSSecureCoding {}
     private func internalUpdateOrLinkPhoneNumber(credential: PhoneAuthCredential,
                                                  isLinkOperation: Bool,
                                                  completion: @escaping (Error?) -> Void) {
-      internalGetToken { accessToken, error in
+      internalGetToken(backend: backend) { accessToken, error in
         if let error {
           completion(error)
           return
@@ -1335,7 +1340,7 @@ extension User: NSSecureCoding {}
           request.accessToken = accessToken
           Task {
             do {
-              let verifyResponse = try await AuthBackend.call(with: request)
+              let verifyResponse = try await self.backend.call(with: request)
               guard let idToken = verifyResponse.idToken,
                     let refreshToken = verifyResponse.refreshToken else {
                 fatalError("Internal Auth Error: missing token in internalUpdateOrLinkPhoneNumber")
@@ -1375,7 +1380,7 @@ extension User: NSSecureCoding {}
                     password: String,
                     authResult: AuthDataResult,
                     _ completion: ((AuthDataResult?, Error?) -> Void)?) {
-    internalGetToken { accessToken, error in
+    internalGetToken(backend: backend) { accessToken, error in
       guard let requestConfiguration = self.auth?.requestConfiguration else {
         fatalError("Internal auth error: missing auth on User")
       }
@@ -1394,7 +1399,7 @@ extension User: NSSecureCoding {}
                                                           action: AuthRecaptchaAction
                                                             .signUpPassword)
           #else
-            let response = try await AuthBackend.call(with: request)
+            let response = try await self.backend.call(with: request)
           #endif
           guard let refreshToken = response.refreshToken,
                 let idToken = response.idToken else {
@@ -1437,7 +1442,7 @@ extension User: NSSecureCoding {}
       let result = AuthDataResult(withUser: self, additionalUserInfo: nil)
       link(withEmail: emailCredential.email, password: password, authResult: result, completion)
     case let .link(link):
-      internalGetToken { accessToken, error in
+      internalGetToken(backend: backend) { accessToken, error in
         var queryItems = AuthWebUtils.parseURL(link)
         if link.count == 0 {
           if let urlComponents = URLComponents(string: link),
@@ -1455,7 +1460,7 @@ extension User: NSSecureCoding {}
         request.idToken = accessToken
         Task {
           do {
-            let response = try await AuthBackend.call(with: request)
+            let response = try await self.backend.call(with: request)
             guard let idToken = response.idToken,
                   let refreshToken = response.refreshToken else {
               fatalError("Internal Auth Error: missing token in EmailLinkSignInResponse")
@@ -1484,7 +1489,7 @@ extension User: NSSecureCoding {}
   #if !os(watchOS)
     private func link(withGameCenterCredential gameCenterCredential: GameCenterAuthCredential,
                       completion: ((AuthDataResult?, Error?) -> Void)?) {
-      internalGetToken { accessToken, error in
+      internalGetToken(backend: backend) { accessToken, error in
         guard let requestConfiguration = self.auth?.requestConfiguration,
               let publicKeyURL = gameCenterCredential.publicKeyURL,
               let signature = gameCenterCredential.signature,
@@ -1503,7 +1508,7 @@ extension User: NSSecureCoding {}
         request.accessToken = accessToken
         Task {
           do {
-            let response = try await AuthBackend.call(with: request)
+            let response = try await self.backend.call(with: request)
             guard let idToken = response.idToken,
                   let refreshToken = response.refreshToken else {
               fatalError("Internal Auth Error: missing token in link(withGameCredential")
@@ -1584,10 +1589,11 @@ extension User: NSSecureCoding {}
   /// - Parameter callback: The block to invoke when the token is available. Invoked asynchronously
   /// on the  global work thread in the future.
   func internalGetToken(forceRefresh: Bool = false,
+                        backend: AuthBackend,
                         callback: @escaping (String?, Error?) -> Void) {
     Task {
       do {
-        let token = try await internalGetTokenAsync(forceRefresh: forceRefresh)
+        let token = try await internalGetTokenAsync(forceRefresh: forceRefresh, backend: backend)
         callback(token, nil)
       } catch {
         callback(nil, error)
@@ -1597,11 +1603,12 @@ extension User: NSSecureCoding {}
 
   /// Retrieves the Firebase authentication token, possibly refreshing it if it has expired.
   /// - Parameter forceRefresh
-  func internalGetTokenAsync(forceRefresh: Bool = false) async throws -> String {
+  func internalGetTokenAsync(forceRefresh: Bool = false,
+                             backend: AuthBackend) async throws -> String {
     var keychainError = false
     do {
       let (token, tokenUpdated) = try await tokenService.fetchAccessToken(
-        forcingRefresh: forceRefresh
+        forcingRefresh: forceRefresh, backend: backend
       )
       if tokenUpdated {
         if let error = updateKeychain() {
@@ -1756,6 +1763,10 @@ extension User: NSSecureCoding {}
     ) as? String
     requestConfiguration = AuthRequestConfiguration(apiKey: apiKey ?? "", appID: appID ?? "")
 
+    // This property will be overwritten later via the `user.auth` property update. For now, a
+    // placeholder is set as the property update should happen right after this intializer.
+    backend = AuthBackend(rpcIssuer: AuthBackendRPCIssuer())
+
     userProfileUpdate = UserProfileUpdate()
     #if os(iOS)
       self.multiFactor = multiFactor ?? MultiFactor()
diff --git a/FirebaseAuth/Sources/Swift/User/UserProfileUpdate.swift b/FirebaseAuth/Sources/Swift/User/UserProfileUpdate.swift
index 74aa5cf5c73..0c51eb9fe83 100644
--- a/FirebaseAuth/Sources/Swift/User/UserProfileUpdate.swift
+++ b/FirebaseAuth/Sources/Swift/User/UserProfileUpdate.swift
@@ -18,13 +18,13 @@ import Foundation
 @available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
 actor UserProfileUpdate {
   func link(user: User, with credential: AuthCredential) async throws -> AuthDataResult {
-    let accessToken = try await user.internalGetTokenAsync()
+    let accessToken = try await user.internalGetTokenAsync(backend: user.backend)
     let request = VerifyAssertionRequest(providerID: credential.provider,
                                          requestConfiguration: user.requestConfiguration)
     credential.prepare(request)
     request.accessToken = accessToken
     do {
-      let response = try await AuthBackend.call(with: request)
+      let response = try await user.backend.call(with: request)
       guard let idToken = response.idToken,
             let refreshToken = response.refreshToken,
             let providerID = response.providerID else {
@@ -48,7 +48,7 @@ actor UserProfileUpdate {
   }
 
   func unlink(user: User, fromProvider provider: String) async throws -> User {
-    let accessToken = try await user.internalGetTokenAsync()
+    let accessToken = try await user.internalGetTokenAsync(backend: user.backend)
     let request = SetAccountInfoRequest(
       accessToken: accessToken, requestConfiguration: user.requestConfiguration
     )
@@ -58,7 +58,7 @@ actor UserProfileUpdate {
     }
     request.deleteProviders = [provider]
     do {
-      let response = try await AuthBackend.call(with: request)
+      let response = try await user.backend.call(with: request)
 
       // We can't just use the provider info objects in SetAccountInfoResponse
       // because they don't have localID and email fields. Remove the specific
@@ -105,7 +105,7 @@ actor UserProfileUpdate {
                                                             SetAccountInfoRequest)
                                       -> Void) async throws {
     let userAccountInfo = try await getAccountInfoRefreshingCache(user)
-    let accessToken = try await user.internalGetTokenAsync()
+    let accessToken = try await user.internalGetTokenAsync(backend: user.backend)
 
     // Mutate setAccountInfoRequest in block
     let setAccountInfoRequest =
@@ -115,7 +115,7 @@ actor UserProfileUpdate {
       )
     changeBlock(userAccountInfo, setAccountInfoRequest)
     do {
-      let accountInfoResponse = try await AuthBackend.call(with: setAccountInfoRequest)
+      let accountInfoResponse = try await user.backend.call(with: setAccountInfoRequest)
       if let idToken = accountInfoResponse.idToken,
          let refreshToken = accountInfoResponse.refreshToken {
         let tokenService = SecureTokenService(
@@ -143,13 +143,13 @@ actor UserProfileUpdate {
       accessTokenExpirationDate: expirationDate,
       refreshToken: refreshToken
     )
-    let accessToken = try await user.internalGetTokenAsync()
+    let accessToken = try await user.internalGetTokenAsync(backend: user.backend)
     let getAccountInfoRequest = GetAccountInfoRequest(
       accessToken: accessToken,
       requestConfiguration: user.requestConfiguration
     )
     do {
-      let response = try await AuthBackend.call(with: getAccountInfoRequest)
+      let response = try await user.backend.call(with: getAccountInfoRequest)
       user.isAnonymous = false
       user.update(withGetAccountInfoResponse: response)
     } catch {
@@ -168,7 +168,7 @@ actor UserProfileUpdate {
   /// - Parameter tokenService: The new token service object.
   /// - Parameter callback: The block to be called in the global auth working queue once finished.
   func setTokenService(user: User, tokenService: SecureTokenService) async throws {
-    _ = try await tokenService.fetchAccessToken(forcingRefresh: false)
+    _ = try await tokenService.fetchAccessToken(forcingRefresh: false, backend: user.backend)
     user.tokenService = tokenService
     if let error = user.updateKeychain() {
       throw error
@@ -180,11 +180,11 @@ actor UserProfileUpdate {
   /// error has been detected. Invoked asynchronously on the auth global work queue in the future.
   func getAccountInfoRefreshingCache(_ user: User) async throws
     -> GetAccountInfoResponse.User {
-    let token = try await user.internalGetTokenAsync()
+    let token = try await user.internalGetTokenAsync(backend: user.backend)
     let request = GetAccountInfoRequest(accessToken: token,
                                         requestConfiguration: user.requestConfiguration)
     do {
-      let accountInfoResponse = try await AuthBackend.call(with: request)
+      let accountInfoResponse = try await user.backend.call(with: request)
       user.update(withGetAccountInfoResponse: accountInfoResponse)
       if let error = user.updateKeychain() {
         throw error
diff --git a/FirebaseAuth/Sources/Swift/Utilities/AuthDefaultUIDelegate.swift b/FirebaseAuth/Sources/Swift/Utilities/AuthDefaultUIDelegate.swift
index 6e7a5b30a57..aa8d3cbec6b 100644
--- a/FirebaseAuth/Sources/Swift/Utilities/AuthDefaultUIDelegate.swift
+++ b/FirebaseAuth/Sources/Swift/Utilities/AuthDefaultUIDelegate.swift
@@ -26,10 +26,10 @@
   ///
   /// This class should be used in the case that a UIDelegate was expected and necessary to
   /// continue a given flow, but none was provided.
-  class AuthDefaultUIDelegate: NSObject, AuthUIDelegate {
+  final class AuthDefaultUIDelegate: NSObject, AuthUIDelegate {
     /// Returns a default AuthUIDelegate object.
     /// - Returns: The default AuthUIDelegate object.
-    class func defaultUIDelegate() -> AuthUIDelegate? {
+    @MainActor static func defaultUIDelegate() -> AuthUIDelegate? {
       if GULAppEnvironmentUtil.isAppExtension() {
         // iOS App extensions should not call [UIApplication sharedApplication], even if
         // UIApplication responds to it.
diff --git a/FirebaseAuth/Sources/Swift/Utilities/AuthRecaptchaVerifier.swift b/FirebaseAuth/Sources/Swift/Utilities/AuthRecaptchaVerifier.swift
index 6919ac40807..859496fac82 100644
--- a/FirebaseAuth/Sources/Swift/Utilities/AuthRecaptchaVerifier.swift
+++ b/FirebaseAuth/Sources/Swift/Utilities/AuthRecaptchaVerifier.swift
@@ -44,7 +44,7 @@
   }
 
   @available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
-  class AuthRecaptchaVerifier {
+  class AuthRecaptchaVerifier: @unchecked Sendable {
     private(set) weak var auth: Auth?
     private(set) var agentConfig: AuthRecaptchaConfig?
     private(set) var tenantConfigs: [String: AuthRecaptchaConfig] = [:]
@@ -149,12 +149,12 @@
         }
       }
 
-      guard let requestConfiguration = auth?.requestConfiguration else {
+      guard let auth = auth else {
         throw AuthErrorUtils.error(code: .recaptchaNotEnabled,
                                    message: "No requestConfiguration for Auth instance")
       }
-      let request = GetRecaptchaConfigRequest(requestConfiguration: requestConfiguration)
-      let response = try await AuthBackend.call(with: request)
+      let request = GetRecaptchaConfigRequest(requestConfiguration: auth.requestConfiguration)
+      let response = try await auth.backend.call(with: request)
       AuthLog.logInfo(code: "I-AUT000029", message: "reCAPTCHA config retrieval succeeded.")
       // Response's site key is of the format projects/<project-id>/keys/<site-key>'
       guard let keys = response.recaptchaKey?.components(separatedBy: "/"),
@@ -179,7 +179,7 @@
       }
       let config = AuthRecaptchaConfig(siteKey: siteKey, enablementStatus: enablementStatus)
 
-      if let tenantID = auth?.tenantID {
+      if let tenantID = auth.tenantID {
         tenantConfigs[tenantID] = config
       } else {
         agentConfig = config
diff --git a/FirebaseAuth/Sources/Swift/Utilities/AuthWebUtils.swift b/FirebaseAuth/Sources/Swift/Utilities/AuthWebUtils.swift
index 2231c040023..69210b9326b 100644
--- a/FirebaseAuth/Sources/Swift/Utilities/AuthWebUtils.swift
+++ b/FirebaseAuth/Sources/Swift/Utilities/AuthWebUtils.swift
@@ -98,7 +98,8 @@ class AuthWebUtils {
     return urlComponents.first
   }
 
-  static func fetchAuthDomain(withRequestConfiguration requestConfiguration: AuthRequestConfiguration)
+  static func fetchAuthDomain(withRequestConfiguration requestConfiguration: AuthRequestConfiguration,
+                              backend: AuthBackend)
     async throws -> String {
     if let emulatorHostAndPort = requestConfiguration.emulatorHostAndPort {
       // If we are using the auth emulator, we do not want to call the GetProjectConfig endpoint.
@@ -107,7 +108,7 @@ class AuthWebUtils {
     }
 
     let request = GetProjectConfigRequest(requestConfiguration: requestConfiguration)
-    let response = try await AuthBackend.call(with: request)
+    let response = try await backend.call(with: request)
 
     // Look up an authorized domain ends with one of the supportedAuthDomains.
     // The sequence of supportedAuthDomains matters. ("firebaseapp.com", "web.app")
diff --git a/FirebaseAuth/Tests/SampleSwift/AuthenticationExample/ViewControllers/AuthViewController.swift b/FirebaseAuth/Tests/SampleSwift/AuthenticationExample/ViewControllers/AuthViewController.swift
index fdde2e0757d..e9567a69e9d 100644
--- a/FirebaseAuth/Tests/SampleSwift/AuthenticationExample/ViewControllers/AuthViewController.swift
+++ b/FirebaseAuth/Tests/SampleSwift/AuthenticationExample/ViewControllers/AuthViewController.swift
@@ -481,7 +481,7 @@ class AuthViewController: UIViewController, DataSourceProviderDelegate {
 
       Task {
         do {
-          let verifyResponse = try await AuthBackend.call(with: request)
+          let verifyResponse = try await AppManager.shared.auth().backend.call(with: request)
 
           guard let receipt = verifyResponse.receipt,
                 let timeoutDate = verifyResponse.suggestedTimeOutDate else {
@@ -510,7 +510,7 @@ class AuthViewController: UIViewController, DataSourceProviderDelegate {
             )
 
             do {
-              _ = try await AuthBackend.call(with: request)
+              _ = try await AppManager.shared.auth().backend.call(with: request)
               print("Verify iOS client succeeded")
             } catch {
               print("Verify iOS Client failed: \(error.localizedDescription)")
diff --git a/FirebaseAuth/Tests/Unit/AuthBackendTests.swift b/FirebaseAuth/Tests/Unit/AuthBackendTests.swift
index a7a484a7d5d..5feaf239e3b 100644
--- a/FirebaseAuth/Tests/Unit/AuthBackendTests.swift
+++ b/FirebaseAuth/Tests/Unit/AuthBackendTests.swift
@@ -41,7 +41,7 @@ class AuthBackendTests: RPCBaseTests {
     let request = FakeRequest(withEncodingError: encodingError)
 
     do {
-      let _ = try await AuthBackend.call(with: request)
+      let _ = try await authBackend.call(with: request)
       XCTFail("Expected to throw")
     } catch {
       let rpcError = error as NSError
@@ -71,7 +71,7 @@ class AuthBackendTests: RPCBaseTests {
   func testBodyDataSerializationError() async throws {
     let request = FakeRequest(withRequestBody: ["unencodable": self])
     do {
-      let _ = try await AuthBackend.call(with: request)
+      let _ = try await authBackend.call(with: request)
       XCTFail("Expected to throw")
     } catch {
       let rpcError = error as NSError
@@ -99,7 +99,7 @@ class AuthBackendTests: RPCBaseTests {
       try self.rpcIssuer.respond(withData: nil, error: responseError)
     }
     do {
-      let _ = try await AuthBackend.call(with: request)
+      let _ = try await authBackend.call(with: request)
       XCTFail("Expected to throw")
     } catch {
       let rpcError = error as NSError
@@ -131,7 +131,7 @@ class AuthBackendTests: RPCBaseTests {
       try self.rpcIssuer.respond(withData: data, error: responseError)
     }
     do {
-      let _ = try await AuthBackend.call(with: request)
+      let _ = try await authBackend.call(with: request)
       XCTFail("Expected to throw")
     } catch {
       let rpcError = error as NSError
@@ -168,7 +168,7 @@ class AuthBackendTests: RPCBaseTests {
       try self.rpcIssuer.respond(withData: data, error: nil)
     }
     do {
-      let _ = try await AuthBackend.call(with: request)
+      let _ = try await authBackend.call(with: request)
       XCTFail("Expected to throw")
     } catch {
       let rpcError = error as NSError
@@ -210,7 +210,7 @@ class AuthBackendTests: RPCBaseTests {
       try self.rpcIssuer.respond(withData: data, error: responseError)
     }
     do {
-      let _ = try await AuthBackend.call(with: request)
+      let _ = try await authBackend.call(with: request)
       XCTFail("Expected to throw")
     } catch {
       let rpcError = error as NSError
@@ -252,7 +252,7 @@ class AuthBackendTests: RPCBaseTests {
       try self.rpcIssuer.respond(withData: data, error: nil)
     }
     do {
-      let _ = try await AuthBackend.call(with: request)
+      let _ = try await authBackend.call(with: request)
       XCTFail("Expected to throw")
     } catch {
       let rpcError = error as NSError
@@ -287,7 +287,7 @@ class AuthBackendTests: RPCBaseTests {
                                  error: responseError)
     }
     do {
-      let _ = try await AuthBackend.call(with: request)
+      let _ = try await authBackend.call(with: request)
       XCTFail("Expected to throw")
     } catch {
       let rpcError = error as NSError
@@ -329,7 +329,7 @@ class AuthBackendTests: RPCBaseTests {
       )
     }
     do {
-      let _ = try await AuthBackend.call(with: request)
+      let _ = try await authBackend.call(with: request)
       XCTFail("Expected to throw")
     } catch {
       let rpcError = error as NSError
@@ -356,7 +356,7 @@ class AuthBackendTests: RPCBaseTests {
                                  error: responseError)
     }
     do {
-      let _ = try await AuthBackend.call(with: request)
+      let _ = try await authBackend.call(with: request)
       XCTFail("Expected to throw")
     } catch {
       let rpcError = error as NSError
@@ -398,7 +398,7 @@ class AuthBackendTests: RPCBaseTests {
                                  error: responseError)
     }
     do {
-      let _ = try await AuthBackend.call(with: request)
+      let _ = try await authBackend.call(with: request)
       XCTFail("Expected to throw")
     } catch {
       let rpcError = error as NSError
@@ -436,7 +436,7 @@ class AuthBackendTests: RPCBaseTests {
       let _ = try self.rpcIssuer.respond(withJSON: [:], error: responseError)
     }
     do {
-      let _ = try await AuthBackend.call(with: request)
+      let _ = try await authBackend.call(with: request)
       XCTFail("Expected to throw")
     } catch {
       let rpcError = error as NSError
@@ -473,7 +473,7 @@ class AuthBackendTests: RPCBaseTests {
       try self.rpcIssuer.respond(serverErrorMessage: customErrorMessage, error: responseError)
     }
     do {
-      let _ = try await AuthBackend.call(with: FakeRequest(withRequestBody: [:]))
+      let _ = try await authBackend.call(with: FakeRequest(withRequestBody: [:]))
       XCTFail("Expected to throw")
     } catch {
       let rpcError = error as NSError
@@ -497,7 +497,7 @@ class AuthBackendTests: RPCBaseTests {
     }
     do {
       let request = FakeDecodingErrorRequest(withRequestBody: [:])
-      let _ = try await AuthBackend.call(with: request)
+      let _ = try await authBackend.call(with: request)
       XCTFail("Expected to throw")
     } catch {
       let rpcError = error as NSError
@@ -528,7 +528,7 @@ class AuthBackendTests: RPCBaseTests {
       // value it was given.
       try self.rpcIssuer.respond(withJSON: [kTestKey: kTestValue])
     }
-    let rpcResponse = try await AuthBackend.call(with: FakeRequest(withRequestBody: [:]))
+    let rpcResponse = try await authBackend.call(with: FakeRequest(withRequestBody: [:]))
     XCTAssertEqual(try XCTUnwrap(rpcResponse.receivedValue), kTestValue)
   }
 
@@ -593,7 +593,7 @@ class AuthBackendTests: RPCBaseTests {
         // Force return from async post
         try self.rpcIssuer.respond(withJSON: [:])
       }
-      _ = try? await AuthBackend.call(with: request)
+      _ = try? await authBackend.call(with: request)
 
       // Then
       let expectedHeader = HeartbeatLoggingTestUtils.nonEmptyHeartbeatsPayload.headerValue()
@@ -620,7 +620,7 @@ class AuthBackendTests: RPCBaseTests {
         // Just force return from async call.
         try self.rpcIssuer.respond(withJSON: [:])
       }
-      _ = try? await AuthBackend.call(with: request)
+      _ = try? await authBackend.call(with: request)
 
       let completeRequest = await rpcIssuer.completeRequest.value
       let headerValue = completeRequest.value(forHTTPHeaderField: "X-Firebase-AppCheck")
@@ -650,7 +650,7 @@ class AuthBackendTests: RPCBaseTests {
         // Force return from async post
         try self.rpcIssuer.respond(withJSON: [:])
       }
-      _ = try? await AuthBackend.call(with: request)
+      _ = try? await authBackend.call(with: request)
 
       // Then
       let completeRequest = await rpcIssuer.completeRequest.value
@@ -713,7 +713,7 @@ class AuthBackendTests: RPCBaseTests {
 
   private struct FakeResponse: AuthRPCResponse {
     var receivedValue: String?
-    mutating func setFields(dictionary: [String: AnyHashable]) throws {
+    init(dictionary: [String: AnyHashable]) throws {
       receivedValue = dictionary["TestKey"] as? String
     }
   }
@@ -739,7 +739,7 @@ class AuthBackendTests: RPCBaseTests {
   }
 
   private struct FakeDecodingErrorResponse: AuthRPCResponse {
-    mutating func setFields(dictionary: [String: AnyHashable]) throws {
+    init(dictionary: [String: AnyHashable]) throws {
       throw NSError(domain: "dummy", code: -1)
     }
   }
diff --git a/FirebaseAuth/Tests/Unit/AuthTests.swift b/FirebaseAuth/Tests/Unit/AuthTests.swift
index 1167bf22ca2..f84eb33d70f 100644
--- a/FirebaseAuth/Tests/Unit/AuthTests.swift
+++ b/FirebaseAuth/Tests/Unit/AuthTests.swift
@@ -47,7 +47,8 @@ class AuthTests: RPCBaseTests {
     #endif // (os(macOS) && !FIREBASE_AUTH_TESTING_USE_MACOS_KEYCHAIN) || SWIFT_PACKAGE
     auth = Auth(
       app: FirebaseApp.app(name: name)!,
-      keychainStorageProvider: keychainStorageProvider
+      keychainStorageProvider: keychainStorageProvider,
+      backend: authBackend
     )
 
     // Set authDispatcherCallback implementation in order to save the token refresh task for later
diff --git a/FirebaseAuth/Tests/Unit/CreateAuthURITests.swift b/FirebaseAuth/Tests/Unit/CreateAuthURITests.swift
index af1f54bce28..334091d21fd 100644
--- a/FirebaseAuth/Tests/Unit/CreateAuthURITests.swift
+++ b/FirebaseAuth/Tests/Unit/CreateAuthURITests.swift
@@ -75,7 +75,7 @@ class CreateAuthURITests: RPCBaseTests {
     rpcIssuer?.respondBlock = {
       try self.rpcIssuer?.respond(withJSON: [kAuthUriKey: kTestAuthUri])
     }
-    let rpcResponse = try await AuthBackend.call(with: makeAuthURIRequest())
+    let rpcResponse = try await authBackend.call(with: makeAuthURIRequest())
     XCTAssertEqual(rpcResponse.authURI, kTestAuthUri)
   }
 
@@ -89,7 +89,7 @@ class CreateAuthURITests: RPCBaseTests {
         .respond(withJSON: ["kind": kTestExpectedKind,
                             "allProviders": [kTestProviderID1, kTestProviderID2]])
     }
-    let rpcResponse = try await AuthBackend.call(with: makeAuthURIRequest())
+    let rpcResponse = try await authBackend.call(with: makeAuthURIRequest())
 
     XCTAssertEqual(rpcIssuer?.requestURL?.absoluteString, kExpectedAPIURL)
     XCTAssertEqual(rpcIssuer?.decodedRequest?["identifier"] as? String, kTestIdentifier)
diff --git a/FirebaseAuth/Tests/Unit/DeleteAccountTests.swift b/FirebaseAuth/Tests/Unit/DeleteAccountTests.swift
index ae213aa8464..a968a02e3e8 100644
--- a/FirebaseAuth/Tests/Unit/DeleteAccountTests.swift
+++ b/FirebaseAuth/Tests/Unit/DeleteAccountTests.swift
@@ -64,7 +64,7 @@ class DeleteAccountTests: RPCBaseTests {
     rpcIssuer?.respondBlock = {
       try self.rpcIssuer?.respond(withJSON: [:])
     }
-    let rpcResponse = try await AuthBackend.call(with: makeDeleteAccountRequest())
+    let rpcResponse = try await authBackend.call(with: makeDeleteAccountRequest())
     XCTAssertNotNil(rpcResponse)
   }
 
diff --git a/FirebaseAuth/Tests/Unit/EmailLinkSignInTests.swift b/FirebaseAuth/Tests/Unit/EmailLinkSignInTests.swift
index 2cdd4943653..ce4b2dd57d5 100644
--- a/FirebaseAuth/Tests/Unit/EmailLinkSignInTests.swift
+++ b/FirebaseAuth/Tests/Unit/EmailLinkSignInTests.swift
@@ -65,7 +65,7 @@ class EmailLinkSignInTests: RPCBaseTests {
       XCTAssertNil(requestDictionary[self.kIDTokenKey])
       try self.rpcIssuer?.respond(withJSON: [:]) // unblock the await
     }
-    let _ = try await AuthBackend.call(with: makeEmailLinkSignInRequest())
+    let _ = try await authBackend.call(with: makeEmailLinkSignInRequest())
   }
 
   /** @fn testEmailLinkRequestCreationOptional
@@ -87,7 +87,7 @@ class EmailLinkSignInTests: RPCBaseTests {
       XCTAssertEqual(requestDictionary[self.kIDTokenKey], kTestIDToken)
       try self.rpcIssuer?.respond(withJSON: [:]) // unblock the await
     }
-    let _ = try await AuthBackend.call(with: request)
+    let _ = try await authBackend.call(with: request)
   }
 
   func testEmailLinkSignInErrors() async throws {
@@ -115,7 +115,7 @@ class EmailLinkSignInTests: RPCBaseTests {
                                              "expiresIn": "\(kTestTokenExpirationTimeInterval)",
                                              "refreshToken": kTestRefreshToken])
     }
-    let response = try await AuthBackend.call(with: makeEmailLinkSignInRequest())
+    let response = try await authBackend.call(with: makeEmailLinkSignInRequest())
 
     XCTAssertEqual(response.idToken, kTestIDTokenResponse)
     XCTAssertEqual(response.email, kTestEmailResponse)
diff --git a/FirebaseAuth/Tests/Unit/GetAccountInfoTests.swift b/FirebaseAuth/Tests/Unit/GetAccountInfoTests.swift
index 87a294c0ef2..dff1e74936e 100644
--- a/FirebaseAuth/Tests/Unit/GetAccountInfoTests.swift
+++ b/FirebaseAuth/Tests/Unit/GetAccountInfoTests.swift
@@ -100,7 +100,7 @@ class GetAccountInfoTests: RPCBaseTests {
     rpcIssuer?.respondBlock = {
       try self.rpcIssuer?.respond(withJSON: ["users": usersIn])
     }
-    let rpcResponse = try await AuthBackend.call(with: makeGetAccountInfoRequest())
+    let rpcResponse = try await authBackend.call(with: makeGetAccountInfoRequest())
 
     let users = try XCTUnwrap(rpcResponse.users)
     XCTAssertGreaterThan(users.count, 0)
diff --git a/FirebaseAuth/Tests/Unit/GetOOBConfirmationCodeTests.swift b/FirebaseAuth/Tests/Unit/GetOOBConfirmationCodeTests.swift
index b9fe798f57d..631bab3a723 100644
--- a/FirebaseAuth/Tests/Unit/GetOOBConfirmationCodeTests.swift
+++ b/FirebaseAuth/Tests/Unit/GetOOBConfirmationCodeTests.swift
@@ -199,7 +199,7 @@ class GetOOBConfirmationCodeTests: RPCBaseTests {
       rpcIssuer?.respondBlock = {
         try self.rpcIssuer?.respond(withJSON: [self.kOOBCodeKey: self.kTestOOBCode])
       }
-      let response = try await AuthBackend.call(with: request())
+      let response = try await authBackend.call(with: request())
       XCTAssertEqual(response.OOBCode, kTestOOBCode)
     }
   }
@@ -217,7 +217,7 @@ class GetOOBConfirmationCodeTests: RPCBaseTests {
       rpcIssuer?.respondBlock = {
         try self.rpcIssuer?.respond(withJSON: [:])
       }
-      let response = try await AuthBackend.call(with: request())
+      let response = try await authBackend.call(with: request())
       XCTAssertNil(response.OOBCode)
     }
   }
diff --git a/FirebaseAuth/Tests/Unit/GetProjectConfigTests.swift b/FirebaseAuth/Tests/Unit/GetProjectConfigTests.swift
index 107a5c33b4f..6dbe4c644c6 100644
--- a/FirebaseAuth/Tests/Unit/GetProjectConfigTests.swift
+++ b/FirebaseAuth/Tests/Unit/GetProjectConfigTests.swift
@@ -60,7 +60,7 @@ class GetProjectConfigTests: RPCBaseTests {
       try self.rpcIssuer?.respond(withJSON: ["projectId": kTestProjectID,
                                              "authorizedDomains": [kTestDomain1, kTestDomain2]])
     }
-    let rpcResponse = try await AuthBackend.call(with: makeGetProjectConfigRequest())
+    let rpcResponse = try await authBackend.call(with: makeGetProjectConfigRequest())
     XCTAssertEqual(rpcResponse.projectID, kTestProjectID)
     XCTAssertEqual(rpcResponse.authorizedDomains?.first, kTestDomain1)
     XCTAssertEqual(rpcResponse.authorizedDomains?[1], kTestDomain2)
diff --git a/FirebaseAuth/Tests/Unit/GetRecaptchaConfigTests.swift b/FirebaseAuth/Tests/Unit/GetRecaptchaConfigTests.swift
index df64689c7c0..75149c38d45 100644
--- a/FirebaseAuth/Tests/Unit/GetRecaptchaConfigTests.swift
+++ b/FirebaseAuth/Tests/Unit/GetRecaptchaConfigTests.swift
@@ -24,7 +24,7 @@ class GetRecaptchaConfigTests: RPCBaseTests {
    */
   func testGetRecaptchaConfigRequest() async throws {
     let request = GetRecaptchaConfigRequest(requestConfiguration: makeRequestConfiguration())
-    //    let _ = try await AuthBackend.call(with: request)
+    //    let _ = try await authBackend.call(with: request)
     XCTAssertFalse(request.containsPostBody)
 
     // Confirm that the request has no decoded body as it is get request.
@@ -47,7 +47,7 @@ class GetRecaptchaConfigTests: RPCBaseTests {
     let request = GetRecaptchaConfigRequest(requestConfiguration: makeRequestConfiguration())
 
     rpcIssuer.recaptchaSiteKey = kTestRecaptchaKey
-    let response = try await AuthBackend.call(with: request)
+    let response = try await authBackend.call(with: request)
     XCTAssertEqual(response.recaptchaKey, kTestRecaptchaKey)
     XCTAssertNil(response.enforcementState)
   }
diff --git a/FirebaseAuth/Tests/Unit/OAuthProviderTests.swift b/FirebaseAuth/Tests/Unit/OAuthProviderTests.swift
index 6f1ed895b0a..a5a330babf7 100644
--- a/FirebaseAuth/Tests/Unit/OAuthProviderTests.swift
+++ b/FirebaseAuth/Tests/Unit/OAuthProviderTests.swift
@@ -282,6 +282,10 @@ import FirebaseCore
         .replacingOccurrences(of: ")", with: "")
       FirebaseApp.configure(name: strippedName, options: options)
       OAuthProviderTests.auth = Auth.auth(app: FirebaseApp.app(name: strippedName)!)
+      OAuthProviderTests.auth = Auth(
+        app: FirebaseApp.app(name: strippedName)!,
+        backend: authBackend
+      )
       OAuthProviderTests.auth?.mainBundleUrlTypes =
         [["CFBundleURLSchemes": [scheme]]]
     }
diff --git a/FirebaseAuth/Tests/Unit/PhoneAuthProviderTests.swift b/FirebaseAuth/Tests/Unit/PhoneAuthProviderTests.swift
index 0030c52776d..9a319ea9755 100644
--- a/FirebaseAuth/Tests/Unit/PhoneAuthProviderTests.swift
+++ b/FirebaseAuth/Tests/Unit/PhoneAuthProviderTests.swift
@@ -662,7 +662,7 @@
       let strippedName = functionName.replacingOccurrences(of: "(", with: "")
         .replacingOccurrences(of: ")", with: "")
       FirebaseApp.configure(name: strippedName, options: options)
-      let auth = Auth.auth(app: FirebaseApp.app(name: strippedName)!)
+      let auth = Auth(app: FirebaseApp.app(name: strippedName)!, backend: authBackend)
 
       kAuthGlobalWorkQueue.sync {
         // Wait for Auth protectedDataInitialization to finish.
diff --git a/FirebaseAuth/Tests/Unit/RPCBaseTests.swift b/FirebaseAuth/Tests/Unit/RPCBaseTests.swift
index 009289a1b44..9a8f9026ea9 100644
--- a/FirebaseAuth/Tests/Unit/RPCBaseTests.swift
+++ b/FirebaseAuth/Tests/Unit/RPCBaseTests.swift
@@ -68,15 +68,16 @@ class RPCBaseTests: XCTestCase {
   let kTestIdentifier = "Identifier"
 
   var rpcIssuer: FakeBackendRPCIssuer!
+  var authBackend: AuthBackend!
 
   override func setUp() {
     rpcIssuer = FakeBackendRPCIssuer()
-    AuthBackend.setTestRPCIssuer(issuer: rpcIssuer)
+    authBackend = AuthBackend(rpcIssuer: rpcIssuer)
   }
 
   override func tearDown() {
     rpcIssuer = nil
-    AuthBackend.resetRPCIssuer()
+    authBackend = nil
   }
 
   /** @fn checkRequest
@@ -99,7 +100,7 @@ class RPCBaseTests: XCTestCase {
       // Dummy response to unblock await.
       let _ = try self.rpcIssuer?.respond(withJSON: [:])
     }
-    let _ = try await AuthBackend.call(with: request)
+    let _ = try await authBackend.call(with: request)
   }
 
   /** @fn checkBackendError
@@ -123,7 +124,7 @@ class RPCBaseTests: XCTestCase {
       }
     }
     do {
-      let _ = try await AuthBackend.call(with: request)
+      let _ = try await authBackend.call(with: request)
       XCTFail("Did not throw expected error")
       return
     } catch {
diff --git a/FirebaseAuth/Tests/Unit/ResetPasswordTests.swift b/FirebaseAuth/Tests/Unit/ResetPasswordTests.swift
index 7fd7f346d3d..a3220f3ee41 100644
--- a/FirebaseAuth/Tests/Unit/ResetPasswordTests.swift
+++ b/FirebaseAuth/Tests/Unit/ResetPasswordTests.swift
@@ -82,7 +82,7 @@ class ResetPasswordTests: RPCBaseTests {
       try self.rpcIssuer?.respond(withJSON: ["email": kTestEmail,
                                              "requestType": kExpectedResetPasswordRequestType])
     }
-    let rpcResponse = try await AuthBackend.call(with: makeResetPasswordRequest())
+    let rpcResponse = try await authBackend.call(with: makeResetPasswordRequest())
 
     XCTAssertEqual(rpcResponse.email, kTestEmail)
     XCTAssertEqual(rpcResponse.requestType, kExpectedResetPasswordRequestType)
diff --git a/FirebaseAuth/Tests/Unit/RevokeTokenTests.swift b/FirebaseAuth/Tests/Unit/RevokeTokenTests.swift
index 945e1e1ee1b..f55f42514d7 100644
--- a/FirebaseAuth/Tests/Unit/RevokeTokenTests.swift
+++ b/FirebaseAuth/Tests/Unit/RevokeTokenTests.swift
@@ -53,7 +53,7 @@ class RevokeTokenTests: RPCBaseTests {
     rpcIssuer.respondBlock = {
       try self.rpcIssuer?.respond(withJSON: [:])
     }
-    let rpcResponse = try await AuthBackend.call(with: makeRevokeTokenRequest())
+    let rpcResponse = try await authBackend.call(with: makeRevokeTokenRequest())
     XCTAssertNotNil(rpcResponse)
   }
 
diff --git a/FirebaseAuth/Tests/Unit/SendVerificationCodeTests.swift b/FirebaseAuth/Tests/Unit/SendVerificationCodeTests.swift
index aa5a30686b6..d6b4b42bc14 100644
--- a/FirebaseAuth/Tests/Unit/SendVerificationCodeTests.swift
+++ b/FirebaseAuth/Tests/Unit/SendVerificationCodeTests.swift
@@ -113,7 +113,7 @@ class SendVerificationCodeTests: RPCBaseTests {
     rpcIssuer.respondBlock = {
       try self.rpcIssuer?.respond(withJSON: [kVerificationIDKey: kFakeVerificationID])
     }
-    let rpcResponse = try await AuthBackend.call(with:
+    let rpcResponse = try await authBackend.call(with:
       makeSendVerificationCodeRequest(CodeIdentity.recaptcha(kTestReCAPTCHAToken)))
     XCTAssertNotNil(rpcResponse)
     XCTAssertEqual(rpcResponse.verificationID, kFakeVerificationID)
diff --git a/FirebaseAuth/Tests/Unit/SetAccountInfoTests.swift b/FirebaseAuth/Tests/Unit/SetAccountInfoTests.swift
index 4efe951991a..037116982de 100644
--- a/FirebaseAuth/Tests/Unit/SetAccountInfoTests.swift
+++ b/FirebaseAuth/Tests/Unit/SetAccountInfoTests.swift
@@ -212,7 +212,7 @@ class SetAccountInfoTests: RPCBaseTests {
          kExpiresInKey: kTestExpiresIn,
          kRefreshTokenKey: kTestRefreshToken])
     }
-    let response = try await AuthBackend.call(with: setAccountInfoRequest())
+    let response = try await authBackend.call(with: setAccountInfoRequest())
     XCTAssertEqual(response.providerUserInfo?.first?.photoURL?.absoluteString, kTestPhotoURL)
     XCTAssertEqual(response.idToken, kTestIDToken)
     XCTAssertEqual(response.refreshToken, kTestRefreshToken)
diff --git a/FirebaseAuth/Tests/Unit/SignInWithGameCenterTests.swift b/FirebaseAuth/Tests/Unit/SignInWithGameCenterTests.swift
index 3513e9212c8..515cbd13e87 100644
--- a/FirebaseAuth/Tests/Unit/SignInWithGameCenterTests.swift
+++ b/FirebaseAuth/Tests/Unit/SignInWithGameCenterTests.swift
@@ -99,7 +99,7 @@ class SignInWithGameCenterTests: RPCBaseTests {
         "displayName": kDisplayName,
       ])
     }
-    let rpcResponse = try await AuthBackend.call(with: request)
+    let rpcResponse = try await authBackend.call(with: request)
     XCTAssertNotNil(rpcResponse)
 
     XCTAssertEqual(rpcResponse.idToken, kIDToken)
diff --git a/FirebaseAuth/Tests/Unit/SignUpNewUserTests.swift b/FirebaseAuth/Tests/Unit/SignUpNewUserTests.swift
index 74c271bff6e..a75f6263a79 100644
--- a/FirebaseAuth/Tests/Unit/SignUpNewUserTests.swift
+++ b/FirebaseAuth/Tests/Unit/SignUpNewUserTests.swift
@@ -82,7 +82,7 @@ class SignUpNewUserTests: RPCBaseTests {
         kRefreshTokenKey: kTestRefreshToken,
       ])
     }
-    let rpcResponse = try await AuthBackend.call(with: makeSignUpNewUserRequest())
+    let rpcResponse = try await authBackend.call(with: makeSignUpNewUserRequest())
     XCTAssertEqual(rpcResponse.refreshToken, kTestRefreshToken)
     let expiresIn = try XCTUnwrap(rpcResponse.approximateExpirationDate?.timeIntervalSinceNow)
     XCTAssertEqual(expiresIn, 12345, accuracy: 0.1)
diff --git a/FirebaseAuth/Tests/Unit/UserTests.swift b/FirebaseAuth/Tests/Unit/UserTests.swift
index 77c1449792f..d1f305f7116 100644
--- a/FirebaseAuth/Tests/Unit/UserTests.swift
+++ b/FirebaseAuth/Tests/Unit/UserTests.swift
@@ -33,12 +33,13 @@ class UserTests: RPCBaseTests {
   let kVerificationID = "55432"
   let kPhoneNumber = "555-1234"
 
-  static var auth: Auth?
+  var auth: Auth?
 
-  override class func setUp() {
+  override func setUp() {
+    super.setUp()
     let options = FirebaseOptions(googleAppID: "0:0000000000000:ios:0000000000000000",
                                   gcmSenderID: "00000000000000000-00000000000-000000000")
-    options.apiKey = kFakeAPIKey
+    options.apiKey = Self.kFakeAPIKey
     options.projectID = "myUserProjectID"
     FirebaseApp.configure(name: "test-UserTests", options: options)
     #if (os(macOS) && !FIREBASE_AUTH_TESTING_USE_MACOS_KEYCHAIN) || SWIFT_PACKAGE
@@ -48,13 +49,17 @@ class UserTests: RPCBaseTests {
     #endif // (os(macOS) && !FIREBASE_AUTH_TESTING_USE_MACOS_KEYCHAIN) || SWIFT_PACKAGE
     auth = Auth(
       app: FirebaseApp.app(name: "test-UserTests")!,
-      keychainStorageProvider: keychainStorageProvider
+      keychainStorageProvider: keychainStorageProvider,
+      backend: authBackend
     )
   }
 
   override func tearDown() {
     // Verifies that no tasks are left suspended on the AuthSerialTaskQueue.
-    try? UserTests.auth?.signOut()
+    try? auth?.signOut()
+    auth = nil
+    FirebaseApp.resetApps()
+    super.tearDown()
   }
 
   /** @fn testUserPropertiesAndNSSecureCoding
@@ -415,7 +420,7 @@ class UserTests: RPCBaseTests {
           // Email should not have changed on the client side.
           XCTAssertEqual(user.email, self.kEmail)
           // User is still signed in.
-          XCTAssertEqual(UserTests.auth?.currentUser, user)
+          XCTAssertEqual(self.auth?.currentUser, user)
           expectation.fulfill()
         }
       }
@@ -441,7 +446,7 @@ class UserTests: RPCBaseTests {
           // Email should not have changed on the client side.
           XCTAssertEqual(user.email, self.kEmail)
           // User is no longer signed in..
-          XCTAssertNil(UserTests.auth?.currentUser)
+          XCTAssertNil(self.auth?.currentUser)
           expectation.fulfill()
         }
       }
@@ -457,7 +462,7 @@ class UserTests: RPCBaseTests {
     func testUpdatePhoneSuccess() throws {
       setFakeGetAccountProvider()
       let expectation = self.expectation(description: #function)
-      let auth = try XCTUnwrap(UserTests.auth)
+      let auth = try XCTUnwrap(self.auth)
       signInWithEmailPasswordReturnFakeUser { user in
         do {
           self.rpcIssuer.respondBlock = {
@@ -491,7 +496,7 @@ class UserTests: RPCBaseTests {
     func testUpdatePhoneNumberFailure() throws {
       setFakeGetAccountProvider()
       let expectation = self.expectation(description: #function)
-      let auth = try XCTUnwrap(UserTests.auth)
+      let auth = try XCTUnwrap(self.auth)
       signInWithEmailPasswordReturnFakeUser { user in
         do {
           self.rpcIssuer.respondBlock = {
@@ -523,7 +528,7 @@ class UserTests: RPCBaseTests {
     func testUpdatePhoneNumberFailureAutoSignOut() throws {
       setFakeGetAccountProvider()
       let expectation = self.expectation(description: #function)
-      let auth = try XCTUnwrap(UserTests.auth)
+      let auth = try XCTUnwrap(self.auth)
       signInWithEmailPasswordReturnFakeUser { user in
         do {
           self.rpcIssuer.respondBlock = {
@@ -540,7 +545,7 @@ class UserTests: RPCBaseTests {
             let error = try! XCTUnwrap(rawError)
             XCTAssertEqual((error as NSError).code, AuthErrorCode.userTokenExpired.rawValue)
             // User is no longer signed in.
-            XCTAssertNil(UserTests.auth?.currentUser)
+            XCTAssertNil(self.auth?.currentUser)
             expectation.fulfill()
           }
         }
@@ -579,7 +584,7 @@ class UserTests: RPCBaseTests {
           // Email should not have changed on the client side.
           XCTAssertEqual(user.email, self.kEmail)
           // User is still signed in.
-          XCTAssertEqual(UserTests.auth?.currentUser, user)
+          XCTAssertEqual(self.auth?.currentUser, user)
           expectation.fulfill()
         }
       }
@@ -605,7 +610,7 @@ class UserTests: RPCBaseTests {
           // Email should not have changed on the client side.
           XCTAssertEqual(user.email, self.kEmail)
           // User is still signed in.
-          XCTAssertEqual(UserTests.auth?.currentUser, user)
+          XCTAssertEqual(self.auth?.currentUser, user)
           expectation.fulfill()
         }
       }
@@ -632,7 +637,7 @@ class UserTests: RPCBaseTests {
           // Email should not have changed on the client side.
           XCTAssertEqual(user.email, self.kEmail)
           // User is signed out.
-          XCTAssertNil(UserTests.auth?.currentUser)
+          XCTAssertNil(self.auth?.currentUser)
           expectation.fulfill()
         }
       }
@@ -688,7 +693,7 @@ class UserTests: RPCBaseTests {
           XCTAssertEqual(user.email, self.kEmail)
           XCTAssertEqual(user.displayName, self.kDisplayName)
           // User is still signed in.
-          XCTAssertEqual(UserTests.auth?.currentUser, user)
+          XCTAssertEqual(self.auth?.currentUser, user)
           expectation.fulfill()
         }
       }
@@ -716,7 +721,7 @@ class UserTests: RPCBaseTests {
           // Email should not have changed on the client side.
           XCTAssertEqual(user.email, self.kEmail)
           // User is signed out.
-          XCTAssertNil(UserTests.auth?.currentUser)
+          XCTAssertNil(self.auth?.currentUser)
           expectation.fulfill()
         }
       }
@@ -821,7 +826,7 @@ class UserTests: RPCBaseTests {
           let error = try! XCTUnwrap(rawError)
           XCTAssertEqual((error as NSError).code, AuthErrorCode.quotaExceeded.rawValue)
           // User is still signed in.
-          XCTAssertEqual(UserTests.auth?.currentUser, user)
+          XCTAssertEqual(self.auth?.currentUser, user)
           expectation.fulfill()
         }
       }
@@ -848,7 +853,7 @@ class UserTests: RPCBaseTests {
           let error = try! XCTUnwrap(rawError)
           XCTAssertEqual((error as NSError).code, AuthErrorCode.userTokenExpired.rawValue)
           // User is no longer signed in.
-          XCTAssertNil(UserTests.auth?.currentUser)
+          XCTAssertNil(self.auth?.currentUser)
           expectation.fulfill()
         }
       }
@@ -878,7 +883,7 @@ class UserTests: RPCBaseTests {
           XCTAssertEqual(result.user.email, user.email)
           XCTAssertEqual(result.additionalUserInfo?.isNewUser, false)
           // User is still signed in.
-          XCTAssertEqual(UserTests.auth?.currentUser, user)
+          XCTAssertEqual(self.auth?.currentUser, user)
           expectation.fulfill()
         }
       }
@@ -914,7 +919,7 @@ class UserTests: RPCBaseTests {
           }
           XCTAssertNil(error)
           // Verify that the current user is unchanged.
-          XCTAssertEqual(UserTests.auth?.currentUser, user)
+          XCTAssertEqual(self.auth?.currentUser, user)
           // Verify that the current user and reauthenticated user are not same pointers.
           XCTAssertNotEqual(user, reauthenticatedAuthResult?.user)
           // Verify that anyway the current user and reauthenticated user have same IDs.
@@ -933,7 +938,7 @@ class UserTests: RPCBaseTests {
       }
     }
     waitForExpectations(timeout: 5)
-    try assertUserGoogle(UserTests.auth?.currentUser)
+    try assertUserGoogle(auth?.currentUser)
   }
 
   /** @fn testReauthenticateFailure
@@ -958,7 +963,7 @@ class UserTests: RPCBaseTests {
           // Email should not have changed on the client side.
           XCTAssertEqual(user.email, self.kEmail)
           // User is still signed in.
-          XCTAssertEqual(UserTests.auth?.currentUser, user)
+          XCTAssertEqual(self.auth?.currentUser, user)
           expectation.fulfill()
         }
       }
@@ -987,7 +992,7 @@ class UserTests: RPCBaseTests {
           // Email should not have changed on the client side.
           XCTAssertEqual(user.email, self.kEmail)
           // User is still signed in.
-          XCTAssertEqual(UserTests.auth?.currentUser, user)
+          XCTAssertEqual(self.auth?.currentUser, user)
           expectation.fulfill()
         }
       }
@@ -1001,7 +1006,7 @@ class UserTests: RPCBaseTests {
   func testLinkAndRetrieveDataSuccess() throws {
     setFakeGetAccountProvider()
     let expectation = self.expectation(description: #function)
-    let auth = try XCTUnwrap(UserTests.auth)
+    let auth = try XCTUnwrap(self.auth)
     signInWithFacebookCredential { user in
       XCTAssertNotNil(user)
       do {
@@ -1069,7 +1074,7 @@ class UserTests: RPCBaseTests {
           // Email should not have changed on the client side.
           XCTAssertEqual(user.email, self.kFacebookEmail)
           // User is still signed in.
-          XCTAssertEqual(UserTests.auth?.currentUser, user)
+          XCTAssertEqual(self.auth?.currentUser, user)
           expectation.fulfill()
         }
       }
@@ -1100,7 +1105,7 @@ class UserTests: RPCBaseTests {
             XCTFail("Expected to throw providerAlreadyLinked error.")
           }
           // User is still signed in.
-          XCTAssertEqual(UserTests.auth?.currentUser, user)
+          XCTAssertEqual(self.auth?.currentUser, user)
           expectation.fulfill()
         }
       }
@@ -1130,7 +1135,7 @@ class UserTests: RPCBaseTests {
           let error = try! XCTUnwrap(rawError)
           XCTAssertEqual((error as NSError).code, AuthErrorCode.userDisabled.rawValue)
           // User is signed out.
-          XCTAssertNil(UserTests.auth?.currentUser)
+          XCTAssertNil(self.auth?.currentUser)
           expectation.fulfill()
         }
       }
@@ -1145,7 +1150,7 @@ class UserTests: RPCBaseTests {
   func testLinkEmailAndRetrieveDataSuccess() throws {
     setFakeGetAccountProvider()
     let expectation = self.expectation(description: #function)
-    let auth = try XCTUnwrap(UserTests.auth)
+    let auth = try XCTUnwrap(self.auth)
     signInWithFacebookCredential { user in
       XCTAssertNotNil(user)
       do {
@@ -1213,7 +1218,7 @@ class UserTests: RPCBaseTests {
               XCTFail("Expected to throw providerAlreadyLinked error.")
             }
             // User is still signed in.
-            XCTAssertEqual(UserTests.auth?.currentUser, user)
+            XCTAssertEqual(self.auth?.currentUser, user)
             expectation.fulfill()
           }
         }
@@ -1247,7 +1252,7 @@ class UserTests: RPCBaseTests {
           let error = try! XCTUnwrap(rawError)
           XCTAssertEqual((error as NSError).code, AuthErrorCode.tooManyRequests.rawValue)
           // User is still signed in.
-          XCTAssertEqual(UserTests.auth?.currentUser, user)
+          XCTAssertEqual(self.auth?.currentUser, user)
           expectation.fulfill()
         }
       }
@@ -1277,7 +1282,7 @@ class UserTests: RPCBaseTests {
           let error = try! XCTUnwrap(rawError)
           XCTAssertEqual((error as NSError).code, AuthErrorCode.userTokenExpired.rawValue)
           // User is signed out.
-          XCTAssertNil(UserTests.auth?.currentUser)
+          XCTAssertNil(self.auth?.currentUser)
           expectation.fulfill()
         }
       }
@@ -1307,7 +1312,7 @@ class UserTests: RPCBaseTests {
     func testLinkProviderFailure() throws {
       setFakeGetAccountProvider()
       let expectation = self.expectation(description: #function)
-      let auth = try XCTUnwrap(UserTests.auth)
+      let auth = try XCTUnwrap(self.auth)
       signInWithFacebookCredential { user in
         XCTAssertNotNil(user)
         do {
@@ -1322,7 +1327,7 @@ class UserTests: RPCBaseTests {
             let error = try! XCTUnwrap(rawError)
             XCTAssertEqual((error as NSError).code, AuthErrorCode.userTokenExpired.rawValue)
             // User is signed out.
-            XCTAssertNil(UserTests.auth?.currentUser)
+            XCTAssertNil(self.auth?.currentUser)
             expectation.fulfill()
           }
         }
@@ -1336,7 +1341,7 @@ class UserTests: RPCBaseTests {
     func testReauthenticateWithProviderFailure() throws {
       setFakeGetAccountProvider()
       let expectation = self.expectation(description: #function)
-      let auth = try XCTUnwrap(UserTests.auth)
+      let auth = try XCTUnwrap(self.auth)
       signInWithFacebookCredential { user in
         XCTAssertNotNil(user)
         do {
@@ -1351,7 +1356,7 @@ class UserTests: RPCBaseTests {
             let error = try! XCTUnwrap(rawError)
             XCTAssertEqual((error as NSError).code, AuthErrorCode.userTokenExpired.rawValue)
             // User is still signed in.
-            XCTAssertEqual(UserTests.auth?.currentUser, user)
+            XCTAssertEqual(self.auth?.currentUser, user)
             expectation.fulfill()
           }
         }
@@ -1365,7 +1370,7 @@ class UserTests: RPCBaseTests {
     func testLinkPhoneAuthCredentialSuccess() throws {
       setFakeGetAccountProvider()
       let expectation = self.expectation(description: #function)
-      let auth = try XCTUnwrap(UserTests.auth)
+      let auth = try XCTUnwrap(self.auth)
       signInWithEmailPasswordReturnFakeUser { user in
         XCTAssertNotNil(user)
         self.expectVerifyPhoneNumberRequest(isLink: true)
@@ -1410,7 +1415,7 @@ class UserTests: RPCBaseTests {
     func testUnlinkPhoneAuthCredentialSuccess() throws {
       setFakeGetAccountProvider()
       let expectation = self.expectation(description: #function)
-      let auth = try XCTUnwrap(UserTests.auth)
+      let auth = try XCTUnwrap(self.auth)
       signInWithEmailPasswordReturnFakeUser { user in
         XCTAssertNotNil(user)
         self.expectVerifyPhoneNumberRequest(isLink: true)
@@ -1506,7 +1511,7 @@ class UserTests: RPCBaseTests {
     func testlinkPhoneCredentialAlreadyExistsError() throws {
       setFakeGetAccountProvider()
       let expectation = self.expectation(description: #function)
-      let auth = try XCTUnwrap(UserTests.auth)
+      let auth = try XCTUnwrap(self.auth)
       signInWithEmailPasswordReturnFakeUser { user in
         XCTAssertNotNil(user)
         self.expectVerifyPhoneNumberRequest(isLink: true)
@@ -1668,12 +1673,12 @@ class UserTests: RPCBaseTests {
     }
     // 1. After setting up fakes, sign out and sign in.
     do {
-      try UserTests.auth?.signOut()
+      try auth?.signOut()
     } catch {
       XCTFail("Sign out failed: \(error)")
       return
     }
-    UserTests.auth?.signIn(withEmail: kEmail, password: kFakePassword) { authResult, error in
+    auth?.signIn(withEmail: kEmail, password: kFakePassword) { authResult, error in
       // 4. After the response triggers the callback, verify the returned result.
       XCTAssertTrue(Thread.isMainThread)
       guard let user = authResult?.user else {
@@ -1716,10 +1721,10 @@ class UserTests: RPCBaseTests {
     }
 
     do {
-      try UserTests.auth?.signOut()
+      try auth?.signOut()
       let googleCredential = GoogleAuthProvider.credential(withIDToken: kGoogleIDToken,
                                                            accessToken: kGoogleAccessToken)
-      UserTests.auth?.signIn(with: googleCredential) { authResult, error in
+      auth?.signIn(with: googleCredential) { authResult, error in
         // 4. After the response triggers the callback, verify the returned result.
         XCTAssertTrue(Thread.isMainThread)
         guard let user = authResult?.user else {
@@ -1783,10 +1788,10 @@ class UserTests: RPCBaseTests {
     }
 
     do {
-      try UserTests.auth?.signOut()
+      try auth?.signOut()
       let facebookCredential = FacebookAuthProvider
         .credential(withAccessToken: kFacebookAccessToken)
-      UserTests.auth?.signIn(with: facebookCredential) { authResult, error in
+      auth?.signIn(with: facebookCredential) { authResult, error in
         // 4. After the response triggers the callback, verify the returned result.
         XCTAssertTrue(Thread.isMainThread)
         guard let user = authResult?.user else {
@@ -1838,8 +1843,8 @@ class UserTests: RPCBaseTests {
     }
 
     do {
-      try UserTests.auth?.signOut()
-      UserTests.auth?.signIn(
+      try auth?.signOut()
+      auth?.signIn(
         withEmail: kEmail,
         link: "https://www.google.com?oobCode=aCode&mode=signIn"
       ) { authResult, error in
diff --git a/FirebaseAuth/Tests/Unit/VerifyAssertionTests.swift b/FirebaseAuth/Tests/Unit/VerifyAssertionTests.swift
index 95e131a8760..2fb630a62ce 100644
--- a/FirebaseAuth/Tests/Unit/VerifyAssertionTests.swift
+++ b/FirebaseAuth/Tests/Unit/VerifyAssertionTests.swift
@@ -180,7 +180,7 @@ class VerifyAssertionTests: RPCBaseTests {
         self.kRawUserInfoKey: self.profile,
       ])
     }
-    let rpcResponse = try await AuthBackend.call(with: makeVerifyAssertionRequest())
+    let rpcResponse = try await authBackend.call(with: makeVerifyAssertionRequest())
     XCTAssertEqual(rpcResponse.idToken, kTestIDToken)
     XCTAssertEqual(rpcResponse.refreshToken, kTestRefreshToken)
     XCTAssertEqual(rpcResponse.verifiedProvider, [kTestProvider])
@@ -211,7 +211,7 @@ class VerifyAssertionTests: RPCBaseTests {
         self.kRawUserInfoKey: self.convertToJson(self.profile),
       ])
     }
-    let rpcResponse = try await AuthBackend.call(with: makeVerifyAssertionRequest())
+    let rpcResponse = try await authBackend.call(with: makeVerifyAssertionRequest())
     XCTAssertEqual(rpcResponse.idToken, kTestIDToken)
     XCTAssertEqual(rpcResponse.refreshToken, kTestRefreshToken)
     XCTAssertEqual(rpcResponse.verifiedProvider, [kTestProvider])
diff --git a/FirebaseAuth/Tests/Unit/VerifyClientTests.swift b/FirebaseAuth/Tests/Unit/VerifyClientTests.swift
index 0f7b0c792ca..528cb357c88 100644
--- a/FirebaseAuth/Tests/Unit/VerifyClientTests.swift
+++ b/FirebaseAuth/Tests/Unit/VerifyClientTests.swift
@@ -71,7 +71,7 @@ class VerifyClientTests: RPCBaseTests {
         kSuggestedTimeOutKey: kFakeSuggestedTimeout,
       ])
     }
-    let rpcResponse = try await AuthBackend.call(with: makeVerifyClientRequest())
+    let rpcResponse = try await authBackend.call(with: makeVerifyClientRequest())
     XCTAssertEqual(rpcResponse.receipt, kFakeReceipt)
     let timeOut = try XCTUnwrap(rpcResponse.suggestedTimeOutDate?.timeIntervalSinceNow)
     XCTAssertEqual(timeOut, 1234, accuracy: 0.1)
diff --git a/FirebaseAuth/Tests/Unit/VerifyCustomTokenTests.swift b/FirebaseAuth/Tests/Unit/VerifyCustomTokenTests.swift
index 36fb06d13e6..8e3e052a4b2 100644
--- a/FirebaseAuth/Tests/Unit/VerifyCustomTokenTests.swift
+++ b/FirebaseAuth/Tests/Unit/VerifyCustomTokenTests.swift
@@ -107,7 +107,7 @@ class VerifyCustomTokenTests: RPCBaseTests {
         kIsNewUserKey: true,
       ])
     }
-    let rpcResponse = try await AuthBackend.call(with: makeVerifyCustomTokenRequest())
+    let rpcResponse = try await authBackend.call(with: makeVerifyCustomTokenRequest())
     XCTAssertEqual(rpcResponse.idToken, kTestIDToken)
     XCTAssertEqual(rpcResponse.refreshToken, kTestRefreshToken)
     let expiresIn = try XCTUnwrap(rpcResponse.approximateExpirationDate?.timeIntervalSinceNow)
diff --git a/FirebaseAuth/Tests/Unit/VerifyPasswordTests.swift b/FirebaseAuth/Tests/Unit/VerifyPasswordTests.swift
index 6b831f0ce80..06821bf74c2 100644
--- a/FirebaseAuth/Tests/Unit/VerifyPasswordTests.swift
+++ b/FirebaseAuth/Tests/Unit/VerifyPasswordTests.swift
@@ -171,7 +171,7 @@ class VerifyPasswordTests: RPCBaseTests {
         kPhotoUrlKey: kTestPhotoUrl,
       ])
     }
-    let rpcResponse = try await AuthBackend.call(with: makeVerifyPasswordRequest())
+    let rpcResponse = try await authBackend.call(with: makeVerifyPasswordRequest())
     XCTAssertEqual(rpcResponse.email, kTestEmail)
     XCTAssertEqual(rpcResponse.localID, kTestLocalID)
     XCTAssertEqual(rpcResponse.displayName, kTestDisplayName)
diff --git a/FirebaseAuth/Tests/Unit/VerifyPhoneNumberTests.swift b/FirebaseAuth/Tests/Unit/VerifyPhoneNumberTests.swift
index e6ff2a42434..50fb9cf67e5 100644
--- a/FirebaseAuth/Tests/Unit/VerifyPhoneNumberTests.swift
+++ b/FirebaseAuth/Tests/Unit/VerifyPhoneNumberTests.swift
@@ -116,7 +116,7 @@ import XCTest
           "isNewUser": true,
         ])
       }
-      let rpcResponse = try await AuthBackend.call(with: makeVerifyPhoneNumberRequest())
+      let rpcResponse = try await authBackend.call(with: makeVerifyPhoneNumberRequest())
       XCTAssertEqual(rpcResponse.localID, kTestLocalID)
       XCTAssertEqual(rpcResponse.idToken, kTestIDToken)
       let expiresIn = try XCTUnwrap(rpcResponse.approximateExpirationDate?.timeIntervalSinceNow)
@@ -135,7 +135,7 @@ import XCTest
         ])
       }
       do {
-        let _ = try await AuthBackend.call(with: makeVerifyPhoneNumberRequestWithTemporaryProof())
+        let _ = try await authBackend.call(with: makeVerifyPhoneNumberRequestWithTemporaryProof())
         XCTFail("Expected to throw")
       } catch {
         let rpcError = error as NSError
diff --git a/FirebaseAuthInterop.podspec b/FirebaseAuthInterop.podspec
index 91dbd50ff5b..872de49ce94 100644
--- a/FirebaseAuthInterop.podspec
+++ b/FirebaseAuthInterop.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseAuthInterop'
-  s.version          = '11.5.0'
+  s.version          = '11.6.0'
   s.summary          = 'Interfaces that allow other Firebase SDKs to use Auth functionality.'
 
   s.description      = <<-DESC
diff --git a/FirebaseCombineSwift.podspec b/FirebaseCombineSwift.podspec
index a181b9b1a42..877521ac9a4 100644
--- a/FirebaseCombineSwift.podspec
+++ b/FirebaseCombineSwift.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseCombineSwift'
-  s.version          = '11.0.0'
+  s.version          = '11.6.0'
   s.summary          = 'Swift extensions with Combine support for Firebase'
 
   s.description      = <<-DESC
@@ -51,7 +51,7 @@ for internal testing only. It should not be published.
   s.osx.framework = 'AppKit'
   s.tvos.framework = 'UIKit'
 
-  s.dependency 'FirebaseCore', '11.5'
+  s.dependency 'FirebaseCore', '~> 11.6.0'
   s.dependency 'FirebaseAuth', '~> 11.0'
   s.dependency 'FirebaseFunctions', '~> 11.0'
   s.dependency 'FirebaseFirestore', '~> 11.0'
diff --git a/FirebaseCore.podspec b/FirebaseCore.podspec
index c2ccb23fddc..0587b7c19e2 100644
--- a/FirebaseCore.podspec
+++ b/FirebaseCore.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseCore'
-  s.version          = '11.5.0'
+  s.version          = '11.6.0'
   s.summary          = 'Firebase Core'
 
   s.description      = <<-DESC
@@ -53,7 +53,7 @@ Firebase Core includes FIRApp and FIROptions which provide central configuration
   # Remember to also update version in `cmake/external/GoogleUtilities.cmake`
   s.dependency 'GoogleUtilities/Environment', '~> 8.0'
   s.dependency 'GoogleUtilities/Logger', '~> 8.0'
-  s.dependency 'FirebaseCoreInternal', '11.5'
+  s.dependency 'FirebaseCoreInternal', '~> 11.6.0'
 
   s.pod_target_xcconfig = {
     'GCC_C_LANGUAGE_STANDARD' => 'c99',
diff --git a/FirebaseCoreExtension.podspec b/FirebaseCoreExtension.podspec
index 59dfad21719..cbabe65f98d 100644
--- a/FirebaseCoreExtension.podspec
+++ b/FirebaseCoreExtension.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
     s.name             = 'FirebaseCoreExtension'
-    s.version          = '11.5.0'
+    s.version          = '11.6.0'
     s.summary          = 'Extended FirebaseCore APIs for Firebase product SDKs'
 
     s.description      = <<-DESC
@@ -34,5 +34,5 @@ Pod::Spec.new do |s|
       "#{s.module_name}_Privacy" => 'FirebaseCore/Extension/Resources/PrivacyInfo.xcprivacy'
     }
 
-    s.dependency 'FirebaseCore', '11.5'
+    s.dependency 'FirebaseCore', '~> 11.6.0'
   end
diff --git a/FirebaseCoreInternal.podspec b/FirebaseCoreInternal.podspec
index 30fc10e914a..6cab3696090 100644
--- a/FirebaseCoreInternal.podspec
+++ b/FirebaseCoreInternal.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseCoreInternal'
-  s.version          = '11.5.0'
+  s.version          = '11.6.0'
   s.summary          = 'APIs for internal FirebaseCore usage.'
 
   s.description      = <<-DESC
diff --git a/FirebaseCrashlytics.podspec b/FirebaseCrashlytics.podspec
index 5426a42bbee..fb0d09d97de 100644
--- a/FirebaseCrashlytics.podspec
+++ b/FirebaseCrashlytics.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseCrashlytics'
-  s.version          = '11.5.0'
+  s.version          = '11.6.0'
   s.summary          = 'Best and lightest-weight crash reporting for mobile, desktop and tvOS.'
   s.description      = 'Firebase Crashlytics helps you track, prioritize, and fix stability issues that erode app quality.'
   s.homepage         = 'https://firebase.google.com/'
@@ -59,7 +59,7 @@ Pod::Spec.new do |s|
     cp -f ./Crashlytics/CrashlyticsInputFiles.xcfilelist ./CrashlyticsInputFiles.xcfilelist
   PREPARE_COMMAND_END
 
-  s.dependency 'FirebaseCore', '11.5'
+  s.dependency 'FirebaseCore', '~> 11.6.0'
   s.dependency 'FirebaseInstallations', '~> 11.0'
   s.dependency 'FirebaseSessions', '~> 11.0'
   s.dependency 'FirebaseRemoteConfigInterop', '~> 11.0'
diff --git a/FirebaseDatabase.podspec b/FirebaseDatabase.podspec
index 834211167ba..f6120d4915e 100644
--- a/FirebaseDatabase.podspec
+++ b/FirebaseDatabase.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseDatabase'
-  s.version          = '11.5.0'
+  s.version          = '11.6.0'
   s.summary          = 'Firebase Realtime Database'
 
   s.description      = <<-DESC
@@ -47,7 +47,7 @@ Simplify your iOS development, grow your user base, and monetize more effectivel
   s.macos.frameworks = 'CFNetwork', 'Security', 'SystemConfiguration'
   s.watchos.frameworks = 'CFNetwork', 'Security', 'WatchKit'
   s.dependency 'leveldb-library', '~> 1.22'
-  s.dependency 'FirebaseCore', '11.5'
+  s.dependency 'FirebaseCore', '~> 11.6.0'
   s.dependency 'FirebaseAppCheckInterop', '~> 11.0'
   s.dependency 'FirebaseSharedSwift', '~> 11.0'
   s.dependency 'GoogleUtilities/UserDefaults', '~> 8.0'
diff --git a/FirebaseDynamicLinks.podspec b/FirebaseDynamicLinks.podspec
index 3d6ce244d8c..dda7be4f589 100644
--- a/FirebaseDynamicLinks.podspec
+++ b/FirebaseDynamicLinks.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseDynamicLinks'
-  s.version          = '11.5.0'
+  s.version          = '11.6.0'
   s.summary          = 'Firebase Dynamic Links'
 
   s.description      = <<-DESC
@@ -34,7 +34,7 @@ Firebase Dynamic Links are deep links that enhance user experience and increase
   }
   s.frameworks = 'QuartzCore'
   s.weak_framework = 'WebKit'
-  s.dependency 'FirebaseCore', '11.5'
+  s.dependency 'FirebaseCore', '~> 11.6.0'
 
   s.pod_target_xcconfig = {
     'GCC_C_LANGUAGE_STANDARD' => 'c99',
diff --git a/FirebaseFirestore.podspec b/FirebaseFirestore.podspec
index ff55ec358f1..92f5e3924c8 100644
--- a/FirebaseFirestore.podspec
+++ b/FirebaseFirestore.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseFirestore'
-  s.version          = '11.5.0'
+  s.version          = '11.6.0'
   s.summary          = 'Google Cloud Firestore'
   s.description      = <<-DESC
 Google Cloud Firestore is a NoSQL document database built for automatic scaling, high performance, and ease of application development.
@@ -35,9 +35,9 @@ Google Cloud Firestore is a NoSQL document database built for automatic scaling,
     "#{s.module_name}_Privacy" => 'Firestore/Swift/Source/Resources/PrivacyInfo.xcprivacy'
   }
 
-  s.dependency 'FirebaseCore', '11.5'
-  s.dependency 'FirebaseCoreExtension', '11.5'
-  s.dependency 'FirebaseFirestoreInternal', '11.5.0'
+  s.dependency 'FirebaseCore', '~> 11.6.0'
+  s.dependency 'FirebaseCoreExtension', '~> 11.6.0'
+  s.dependency 'FirebaseFirestoreInternal', '11.6.0'
   s.dependency 'FirebaseSharedSwift', '~> 11.0'
 
 end
diff --git a/FirebaseFirestoreInternal.podspec b/FirebaseFirestoreInternal.podspec
index 33a61dbca85..704b099c0a1 100644
--- a/FirebaseFirestoreInternal.podspec
+++ b/FirebaseFirestoreInternal.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseFirestoreInternal'
-  s.version          = '11.5.0'
+  s.version          = '11.6.0'
   s.summary          = 'Google Cloud Firestore'
 
   s.description      = <<-DESC
@@ -93,7 +93,7 @@ Google Cloud Firestore is a NoSQL document database built for automatic scaling,
   }
 
   s.dependency 'FirebaseAppCheckInterop', '~> 11.0'
-  s.dependency 'FirebaseCore', '11.5'
+  s.dependency 'FirebaseCore', '~> 11.6.0'
 
   abseil_version = '~> 1.20240116.1'
   s.dependency 'abseil/algorithm', abseil_version
diff --git a/FirebaseFunctions.podspec b/FirebaseFunctions.podspec
index fb9d748f4cb..e95980c98ee 100644
--- a/FirebaseFunctions.podspec
+++ b/FirebaseFunctions.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseFunctions'
-  s.version          = '11.5.0'
+  s.version          = '11.6.0'
   s.summary          = 'Cloud Functions for Firebase'
 
   s.description      = <<-DESC
@@ -35,8 +35,8 @@ Cloud Functions for Firebase.
     'FirebaseFunctions/Sources/**/*.swift',
   ]
 
-  s.dependency 'FirebaseCore', '11.5'
-  s.dependency 'FirebaseCoreExtension', '11.5'
+  s.dependency 'FirebaseCore', '~> 11.6.0'
+  s.dependency 'FirebaseCoreExtension', '~> 11.6.0'
   s.dependency 'FirebaseAppCheckInterop', '~> 11.0'
   s.dependency 'FirebaseAuthInterop', '~> 11.0'
   s.dependency 'FirebaseMessagingInterop', '~> 11.0'
diff --git a/FirebaseInAppMessaging.podspec b/FirebaseInAppMessaging.podspec
index 9aa37623b15..53fe204fde8 100644
--- a/FirebaseInAppMessaging.podspec
+++ b/FirebaseInAppMessaging.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseInAppMessaging'
-  s.version          = '11.5.0-beta'
+  s.version          = '11.6.0-beta'
   s.summary          = 'Firebase In-App Messaging for iOS'
 
   s.description      = <<-DESC
@@ -80,7 +80,7 @@ See more product details at https://firebase.google.com/products/in-app-messagin
 
   s.framework = 'UIKit'
 
-  s.dependency 'FirebaseCore', '11.5'
+  s.dependency 'FirebaseCore', '~> 11.6.0'
   s.dependency 'FirebaseInstallations', '~> 11.0'
   s.dependency 'FirebaseABTesting', '~> 11.0'
   s.dependency 'GoogleUtilities/Environment', '~> 8.0'
diff --git a/FirebaseInstallations.podspec b/FirebaseInstallations.podspec
index 377902f1df6..3476e780078 100644
--- a/FirebaseInstallations.podspec
+++ b/FirebaseInstallations.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseInstallations'
-  s.version          = '11.5.0'
+  s.version          = '11.6.0'
   s.summary          = 'Firebase Installations'
 
   s.description      = <<-DESC
@@ -45,7 +45,7 @@ Pod::Spec.new do |s|
   }
 
   s.framework = 'Security'
-  s.dependency 'FirebaseCore', '11.5'
+  s.dependency 'FirebaseCore', '~> 11.6.0'
   s.dependency 'PromisesObjC', '~> 2.4'
   s.dependency 'GoogleUtilities/Environment', '~> 8.0'
   s.dependency 'GoogleUtilities/UserDefaults', '~> 8.0'
diff --git a/FirebaseMLModelDownloader.podspec b/FirebaseMLModelDownloader.podspec
index 6ca985941e8..879282861a3 100644
--- a/FirebaseMLModelDownloader.podspec
+++ b/FirebaseMLModelDownloader.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseMLModelDownloader'
-  s.version          = '11.5.0-beta'
+  s.version          = '11.6.0-beta'
   s.summary          = 'Firebase ML Model Downloader'
 
   s.description      = <<-DESC
@@ -36,8 +36,8 @@ Pod::Spec.new do |s|
   ]
 
   s.framework = 'Foundation'
-  s.dependency 'FirebaseCore', '11.5'
-  s.dependency 'FirebaseCoreExtension', '11.5'
+  s.dependency 'FirebaseCore', '~> 11.6.0'
+  s.dependency 'FirebaseCoreExtension', '~> 11.6.0'
   s.dependency 'FirebaseInstallations', '~> 11.0'
   s.dependency 'GoogleDataTransport', '~> 10.0'
   s.dependency 'GoogleUtilities/UserDefaults', '~> 8.0'
diff --git a/FirebaseMessaging.podspec b/FirebaseMessaging.podspec
index c826363f9e5..95ac97e6631 100644
--- a/FirebaseMessaging.podspec
+++ b/FirebaseMessaging.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseMessaging'
-  s.version          = '11.5.0'
+  s.version          = '11.6.0'
   s.summary          = 'Firebase Messaging'
 
   s.description      = <<-DESC
@@ -62,7 +62,7 @@ device, and it is completely free.
   s.osx.framework = 'SystemConfiguration'
   s.weak_framework = 'UserNotifications'
   s.dependency 'FirebaseInstallations', '~> 11.0'
-  s.dependency 'FirebaseCore', '11.5'
+  s.dependency 'FirebaseCore', '~> 11.6.0'
   s.dependency 'GoogleUtilities/AppDelegateSwizzler', '~> 8.0'
   s.dependency 'GoogleUtilities/Reachability', '~> 8.0'
   s.dependency 'GoogleUtilities/Environment', '~> 8.0'
diff --git a/FirebaseMessagingInterop.podspec b/FirebaseMessagingInterop.podspec
index 001c05f57c4..b95739b71be 100644
--- a/FirebaseMessagingInterop.podspec
+++ b/FirebaseMessagingInterop.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseMessagingInterop'
-  s.version          = '11.5.0'
+  s.version          = '11.6.0'
   s.summary          = 'Interfaces that allow other Firebase SDKs to use Messaging functionality.'
 
   s.description      = <<-DESC
diff --git a/FirebasePerformance.podspec b/FirebasePerformance.podspec
index 1215fa057f4..c35aa20a3cc 100644
--- a/FirebasePerformance.podspec
+++ b/FirebasePerformance.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebasePerformance'
-  s.version          = '11.5.0'
+  s.version          = '11.6.0'
   s.summary          = 'Firebase Performance'
 
   s.description      = <<-DESC
@@ -59,7 +59,7 @@ Firebase Performance library to measure performance of Mobile and Web Apps.
   s.ios.framework = 'CoreTelephony'
   s.framework = 'QuartzCore'
   s.framework = 'SystemConfiguration'
-  s.dependency 'FirebaseCore', '11.5'
+  s.dependency 'FirebaseCore', '~> 11.6.0'
   s.dependency 'FirebaseInstallations', '~> 11.0'
   s.dependency 'FirebaseRemoteConfig', '~> 11.0'
   s.dependency 'FirebaseSessions', '~> 11.0'
diff --git a/FirebaseRemoteConfig.podspec b/FirebaseRemoteConfig.podspec
index d8dfbe3aa84..03eeb4bf80b 100644
--- a/FirebaseRemoteConfig.podspec
+++ b/FirebaseRemoteConfig.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseRemoteConfig'
-  s.version          = '11.5.0'
+  s.version          = '11.6.0'
   s.summary          = 'Firebase Remote Config'
 
   s.description      = <<-DESC
@@ -52,7 +52,7 @@ app update.
   }
   s.dependency 'FirebaseABTesting', '~> 11.0'
   s.dependency 'FirebaseSharedSwift', '~> 11.0'
-  s.dependency 'FirebaseCore', '11.5'
+  s.dependency 'FirebaseCore', '~> 11.6.0'
   s.dependency 'FirebaseInstallations', '~> 11.0'
   s.dependency 'GoogleUtilities/Environment', '~> 8.0'
   s.dependency 'GoogleUtilities/NSData+zlib', '~> 8.0'
diff --git a/FirebaseRemoteConfigInterop.podspec b/FirebaseRemoteConfigInterop.podspec
index 197604250f2..1e8a2078665 100644
--- a/FirebaseRemoteConfigInterop.podspec
+++ b/FirebaseRemoteConfigInterop.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseRemoteConfigInterop'
-  s.version          = '11.5.0'
+  s.version          = '11.6.0'
   s.summary          = 'Interfaces that allow other Firebase SDKs to use Remote Config functionality.'
 
   s.description      = <<-DESC
diff --git a/FirebaseSessions.podspec b/FirebaseSessions.podspec
index f36099d413d..d54cf449d3c 100644
--- a/FirebaseSessions.podspec
+++ b/FirebaseSessions.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseSessions'
-  s.version          = '11.5.0'
+  s.version          = '11.6.0'
   s.summary          = 'Firebase Sessions'
 
   s.description      = <<-DESC
@@ -39,8 +39,8 @@ Pod::Spec.new do |s|
     base_dir + 'SourcesObjC/**/*.{c,h,m,mm}',
   ]
 
-  s.dependency 'FirebaseCore', '11.5'
-  s.dependency 'FirebaseCoreExtension', '11.5'
+  s.dependency 'FirebaseCore', '~> 11.6.0'
+  s.dependency 'FirebaseCoreExtension', '~> 11.6.0'
   s.dependency 'FirebaseInstallations', '~> 11.0'
   s.dependency 'GoogleDataTransport', '~> 10.0'
   s.dependency 'GoogleUtilities/Environment', '~> 8.0'
diff --git a/FirebaseSharedSwift.podspec b/FirebaseSharedSwift.podspec
index ab2345bb104..287e3bef90c 100644
--- a/FirebaseSharedSwift.podspec
+++ b/FirebaseSharedSwift.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name                    = 'FirebaseSharedSwift'
-  s.version                 = '11.5.0'
+  s.version                 = '11.6.0'
   s.summary                 = 'Shared Swift Extensions for Firebase'
 
   s.description      = <<-DESC
diff --git a/FirebaseStorage.podspec b/FirebaseStorage.podspec
index bcbe118149b..753a4b558c5 100644
--- a/FirebaseStorage.podspec
+++ b/FirebaseStorage.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseStorage'
-  s.version          = '11.5.0'
+  s.version          = '11.6.0'
   s.summary          = 'Firebase Storage'
 
   s.description      = <<-DESC
@@ -39,8 +39,8 @@ Firebase Storage provides robust, secure file uploads and downloads from Firebas
 
   s.dependency 'FirebaseAppCheckInterop', '~> 11.0'
   s.dependency 'FirebaseAuthInterop', '~> 11.0'
-  s.dependency 'FirebaseCore', '11.5'
-  s.dependency 'FirebaseCoreExtension', '11.5'
+  s.dependency 'FirebaseCore', '~> 11.6.0'
+  s.dependency 'FirebaseCoreExtension', '~> 11.6.0'
   s.dependency 'GTMSessionFetcher/Core', '>= 3.4', '< 5.0'
   s.dependency 'GoogleUtilities/Environment', '~> 8.0'
 
diff --git a/FirebaseVertexAI.podspec b/FirebaseVertexAI.podspec
index a6aa6ea5b56..fdfe4d0a3e1 100644
--- a/FirebaseVertexAI.podspec
+++ b/FirebaseVertexAI.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseVertexAI'
-  s.version          = '11.5.0'
+  s.version          = '11.6.0'
   s.summary          = 'Vertex AI in Firebase SDK'
 
   s.description      = <<-DESC
@@ -46,8 +46,8 @@ Firebase SDK.
 
   s.dependency 'FirebaseAppCheckInterop', '~> 11.4'
   s.dependency 'FirebaseAuthInterop', '~> 11.4'
-  s.dependency 'FirebaseCore', '11.5'
-  s.dependency 'FirebaseCoreExtension', '11.5'
+  s.dependency 'FirebaseCore', '~> 11.6.0'
+  s.dependency 'FirebaseCoreExtension', '~> 11.6.0'
 
   s.test_spec 'unit' do |unit_tests|
     unit_tests_dir = 'FirebaseVertexAI/Tests/Unit/'
diff --git a/GoogleAppMeasurement.podspec b/GoogleAppMeasurement.podspec
index aa4ec6509b7..25b05e666bc 100644
--- a/GoogleAppMeasurement.podspec
+++ b/GoogleAppMeasurement.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
     s.name             = 'GoogleAppMeasurement'
-    s.version          = '11.5.0'
+    s.version          = '11.6.0'
     s.summary          = 'Shared measurement methods for Google libraries. Not intended for direct use.'
 
     s.description      = <<-DESC
@@ -37,7 +37,7 @@ Pod::Spec.new do |s|
     s.default_subspecs = 'AdIdSupport'
 
     s.subspec 'AdIdSupport' do |ss|
-        ss.dependency 'GoogleAppMeasurement/WithoutAdIdSupport', '11.5.0'
+        ss.dependency 'GoogleAppMeasurement/WithoutAdIdSupport', '11.6.0'
         ss.vendored_frameworks = 'Frameworks/GoogleAppMeasurementIdentitySupport.xcframework'
     end
 
diff --git a/GoogleAppMeasurementOnDeviceConversion.podspec b/GoogleAppMeasurementOnDeviceConversion.podspec
index 8250337d28d..5c9f9f8ca2c 100644
--- a/GoogleAppMeasurementOnDeviceConversion.podspec
+++ b/GoogleAppMeasurementOnDeviceConversion.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
     s.name             = 'GoogleAppMeasurementOnDeviceConversion'
-    s.version          = '11.5.0'
+    s.version          = '11.6.0'
     s.summary          = <<-SUMMARY
     On device conversion measurement plugin for Google App Measurement. Not
     intended for direct use.
diff --git a/Package.swift b/Package.swift
index 1fa4deed10a..73151c6c226 100644
--- a/Package.swift
+++ b/Package.swift
@@ -19,7 +19,7 @@
 import class Foundation.ProcessInfo
 import PackageDescription
 
-let firebaseVersion = "11.5.0"
+let firebaseVersion = "11.6.0"
 
 let package = Package(
   name: "Firebase",
diff --git a/ReleaseTooling/CarthageJSON/FirebaseABTestingBinary.json b/ReleaseTooling/CarthageJSON/FirebaseABTestingBinary.json
index f20a644d7d8..b43f6d31b8d 100644
--- a/ReleaseTooling/CarthageJSON/FirebaseABTestingBinary.json
+++ b/ReleaseTooling/CarthageJSON/FirebaseABTestingBinary.json
@@ -33,6 +33,7 @@
   "11.2.0": "https://dl.google.com/dl/firebase/ios/carthage/11.2.0/FirebaseABTesting-0d51fde82d49f9e8.zip",
   "11.3.0": "https://dl.google.com/dl/firebase/ios/carthage/11.3.0/FirebaseABTesting-2233510ff87da3b6.zip",
   "11.4.0": "https://dl.google.com/dl/firebase/ios/carthage/11.4.0/FirebaseABTesting-4d0b187af6fd8d67.zip",
+  "11.5.0": "https://dl.google.com/dl/firebase/ios/carthage/11.5.0/FirebaseABTesting-0c318b2c019b4484.zip",
   "4.11.0": "https://dl.google.com/dl/firebase/ios/carthage/4.11.0/ABTesting-d0fdf10c43e985b1.zip",
   "4.12.0": "https://dl.google.com/dl/firebase/ios/carthage/4.12.0/ABTesting-d0fdf10c43e985b1.zip",
   "4.9.0": "https://dl.google.com/dl/firebase/ios/carthage/4.9.0/ABTesting-a71d17cadc209af9.zip",
diff --git a/ReleaseTooling/CarthageJSON/FirebaseAdMobBinary.json b/ReleaseTooling/CarthageJSON/FirebaseAdMobBinary.json
index 23252863595..892b10e4152 100644
--- a/ReleaseTooling/CarthageJSON/FirebaseAdMobBinary.json
+++ b/ReleaseTooling/CarthageJSON/FirebaseAdMobBinary.json
@@ -33,6 +33,7 @@
   "11.2.0": "https://dl.google.com/dl/firebase/ios/carthage/11.2.0/Google-Mobile-Ads-SDK-4f24527af297e7f1.zip",
   "11.3.0": "https://dl.google.com/dl/firebase/ios/carthage/11.3.0/Google-Mobile-Ads-SDK-80ba4cb995505158.zip",
   "11.4.0": "https://dl.google.com/dl/firebase/ios/carthage/11.4.0/Google-Mobile-Ads-SDK-3df614a58e6a5fa6.zip",
+  "11.5.0": "https://dl.google.com/dl/firebase/ios/carthage/11.5.0/Google-Mobile-Ads-SDK-34abc42769a452ec.zip",
   "4.11.0": "https://dl.google.com/dl/firebase/ios/carthage/4.11.0/AdMob-8a654a42c33bbcc8.zip",
   "4.12.0": "https://dl.google.com/dl/firebase/ios/carthage/4.12.0/AdMob-63dab3b525b94cd9.zip",
   "4.9.0": "https://dl.google.com/dl/firebase/ios/carthage/4.9.0/AdMob-134752c6180a2a41.zip",
diff --git a/ReleaseTooling/CarthageJSON/FirebaseAnalyticsBinary.json b/ReleaseTooling/CarthageJSON/FirebaseAnalyticsBinary.json
index 7d6c0b1d9c6..6eef13dc1a5 100644
--- a/ReleaseTooling/CarthageJSON/FirebaseAnalyticsBinary.json
+++ b/ReleaseTooling/CarthageJSON/FirebaseAnalyticsBinary.json
@@ -33,6 +33,7 @@
   "11.2.0": "https://dl.google.com/dl/firebase/ios/carthage/11.2.0/FirebaseAnalytics-a93a6c81da535385.zip",
   "11.3.0": "https://dl.google.com/dl/firebase/ios/carthage/11.3.0/FirebaseAnalytics-fd2c71a90d62b88a.zip",
   "11.4.0": "https://dl.google.com/dl/firebase/ios/carthage/11.4.0/FirebaseAnalytics-525b465eb296d09e.zip",
+  "11.5.0": "https://dl.google.com/dl/firebase/ios/carthage/11.5.0/FirebaseAnalytics-7302159af7baa5d6.zip",
   "4.11.0": "https://dl.google.com/dl/firebase/ios/carthage/4.11.0/Analytics-2468c231ebeb7922.zip",
   "4.12.0": "https://dl.google.com/dl/firebase/ios/carthage/4.12.0/Analytics-bc8101d420b896c5.zip",
   "4.9.0": "https://dl.google.com/dl/firebase/ios/carthage/4.9.0/Analytics-d2b6a6b0242db786.zip",
diff --git a/ReleaseTooling/CarthageJSON/FirebaseAnalyticsOnDeviceConversionBinary.json b/ReleaseTooling/CarthageJSON/FirebaseAnalyticsOnDeviceConversionBinary.json
index 18dfed2db67..c1494a9cf81 100644
--- a/ReleaseTooling/CarthageJSON/FirebaseAnalyticsOnDeviceConversionBinary.json
+++ b/ReleaseTooling/CarthageJSON/FirebaseAnalyticsOnDeviceConversionBinary.json
@@ -33,6 +33,7 @@
   "11.2.0": "https://dl.google.com/dl/firebase/ios/carthage/11.2.0/FirebaseAnalyticsOnDeviceConversion-09d94624a2de0ac8.zip",
   "11.3.0": "https://dl.google.com/dl/firebase/ios/carthage/11.3.0/FirebaseAnalyticsOnDeviceConversion-918bc6e0b7a2fd94.zip",
   "11.4.0": "https://dl.google.com/dl/firebase/ios/carthage/11.4.0/FirebaseAnalyticsOnDeviceConversion-1640c514418a23da.zip",
+  "11.5.0": "https://dl.google.com/dl/firebase/ios/carthage/11.5.0/FirebaseAnalyticsOnDeviceConversion-8f2f37c75bba22f1.zip",
   "9.0.0": "https://dl.google.com/dl/firebase/ios/carthage/9.0.0/FirebaseAnalyticsOnDeviceConversion-31aedde70a736b8a.zip",
   "9.1.0": "https://dl.google.com/dl/firebase/ios/carthage/9.1.0/FirebaseAnalyticsOnDeviceConversion-f13b5a47d1e3978d.zip",
   "9.2.0": "https://dl.google.com/dl/firebase/ios/carthage/9.2.0/FirebaseAnalyticsOnDeviceConversion-2ebf567c4d97de12.zip",
diff --git a/ReleaseTooling/CarthageJSON/FirebaseAppCheckBinary.json b/ReleaseTooling/CarthageJSON/FirebaseAppCheckBinary.json
index 2d7321fbe98..ef662dff5d2 100644
--- a/ReleaseTooling/CarthageJSON/FirebaseAppCheckBinary.json
+++ b/ReleaseTooling/CarthageJSON/FirebaseAppCheckBinary.json
@@ -33,6 +33,7 @@
   "11.2.0": "https://dl.google.com/dl/firebase/ios/carthage/11.2.0/FirebaseAppCheck-d0c5f46e6a2bf4a3.zip",
   "11.3.0": "https://dl.google.com/dl/firebase/ios/carthage/11.3.0/FirebaseAppCheck-89c39bdcf0bb90fe.zip",
   "11.4.0": "https://dl.google.com/dl/firebase/ios/carthage/11.4.0/FirebaseAppCheck-9b0c4a9489968b07.zip",
+  "11.5.0": "https://dl.google.com/dl/firebase/ios/carthage/11.5.0/FirebaseAppCheck-8b9bb98738bf8bcf.zip",
   "8.0.0": "https://dl.google.com/dl/firebase/ios/carthage/8.0.0/FirebaseAppCheck-9ef1d217cf057203.zip",
   "8.1.0": "https://dl.google.com/dl/firebase/ios/carthage/8.1.0/FirebaseAppCheck-fc03215d9fe45d3a.zip",
   "8.10.0": "https://dl.google.com/dl/firebase/ios/carthage/8.10.0/FirebaseAppCheck-6ebe9e9539f06003.zip",
diff --git a/ReleaseTooling/CarthageJSON/FirebaseAppDistributionBinary.json b/ReleaseTooling/CarthageJSON/FirebaseAppDistributionBinary.json
index 9aca0a85f2b..6610d08d71d 100644
--- a/ReleaseTooling/CarthageJSON/FirebaseAppDistributionBinary.json
+++ b/ReleaseTooling/CarthageJSON/FirebaseAppDistributionBinary.json
@@ -33,6 +33,7 @@
   "11.2.0": "https://dl.google.com/dl/firebase/ios/carthage/11.2.0/FirebaseAppDistribution-9b05f4873b275347.zip",
   "11.3.0": "https://dl.google.com/dl/firebase/ios/carthage/11.3.0/FirebaseAppDistribution-6d2eccaccfd3145f.zip",
   "11.4.0": "https://dl.google.com/dl/firebase/ios/carthage/11.4.0/FirebaseAppDistribution-20ac94ca344af731.zip",
+  "11.5.0": "https://dl.google.com/dl/firebase/ios/carthage/11.5.0/FirebaseAppDistribution-6d2e83d234fea209.zip",
   "6.31.0": "https://dl.google.com/dl/firebase/ios/carthage/6.31.0/FirebaseAppDistribution-07f6a2cf7f576a8a.zip",
   "6.32.0": "https://dl.google.com/dl/firebase/ios/carthage/6.32.0/FirebaseAppDistribution-a9c4f5db794508ca.zip",
   "6.33.0": "https://dl.google.com/dl/firebase/ios/carthage/6.33.0/FirebaseAppDistribution-448a96d2ade54581.zip",
diff --git a/ReleaseTooling/CarthageJSON/FirebaseAuthBinary.json b/ReleaseTooling/CarthageJSON/FirebaseAuthBinary.json
index 36522271aac..4b42255a58b 100644
--- a/ReleaseTooling/CarthageJSON/FirebaseAuthBinary.json
+++ b/ReleaseTooling/CarthageJSON/FirebaseAuthBinary.json
@@ -33,6 +33,7 @@
   "11.2.0": "https://dl.google.com/dl/firebase/ios/carthage/11.2.0/FirebaseAuth-eade26b5390baf84.zip",
   "11.3.0": "https://dl.google.com/dl/firebase/ios/carthage/11.3.0/FirebaseAuth-93dd2965b3f79b98.zip",
   "11.4.0": "https://dl.google.com/dl/firebase/ios/carthage/11.4.0/FirebaseAuth-5faf6dc3bb16c732.zip",
+  "11.5.0": "https://dl.google.com/dl/firebase/ios/carthage/11.5.0/FirebaseAuth-0c8317aa5649f10f.zip",
   "4.11.0": "https://dl.google.com/dl/firebase/ios/carthage/4.11.0/Auth-0fa76ba0f7956220.zip",
   "4.12.0": "https://dl.google.com/dl/firebase/ios/carthage/4.12.0/Auth-5ddd2b4351012c7a.zip",
   "4.9.0": "https://dl.google.com/dl/firebase/ios/carthage/4.9.0/Auth-5e248984d78d7284.zip",
diff --git a/ReleaseTooling/CarthageJSON/FirebaseCrashlyticsBinary.json b/ReleaseTooling/CarthageJSON/FirebaseCrashlyticsBinary.json
index 7381237c17b..e1e7795e6e5 100644
--- a/ReleaseTooling/CarthageJSON/FirebaseCrashlyticsBinary.json
+++ b/ReleaseTooling/CarthageJSON/FirebaseCrashlyticsBinary.json
@@ -33,6 +33,7 @@
   "11.2.0": "https://dl.google.com/dl/firebase/ios/carthage/11.2.0/FirebaseCrashlytics-13851523ad6df088.zip",
   "11.3.0": "https://dl.google.com/dl/firebase/ios/carthage/11.3.0/FirebaseCrashlytics-282a6f3cf3445787.zip",
   "11.4.0": "https://dl.google.com/dl/firebase/ios/carthage/11.4.0/FirebaseCrashlytics-d5c125d6416f6e0a.zip",
+  "11.5.0": "https://dl.google.com/dl/firebase/ios/carthage/11.5.0/FirebaseCrashlytics-8b3c9a29b8afd9b3.zip",
   "6.15.0": "https://dl.google.com/dl/firebase/ios/carthage/6.15.0/FirebaseCrashlytics-1c6d22d5b73c84fd.zip",
   "6.16.0": "https://dl.google.com/dl/firebase/ios/carthage/6.16.0/FirebaseCrashlytics-938e5fd0e2eab3b3.zip",
   "6.17.0": "https://dl.google.com/dl/firebase/ios/carthage/6.17.0/FirebaseCrashlytics-fa09f0c8f31ed5d9.zip",
diff --git a/ReleaseTooling/CarthageJSON/FirebaseDatabaseBinary.json b/ReleaseTooling/CarthageJSON/FirebaseDatabaseBinary.json
index 99a776b8c34..6e0f6983421 100644
--- a/ReleaseTooling/CarthageJSON/FirebaseDatabaseBinary.json
+++ b/ReleaseTooling/CarthageJSON/FirebaseDatabaseBinary.json
@@ -33,6 +33,7 @@
   "11.2.0": "https://dl.google.com/dl/firebase/ios/carthage/11.2.0/FirebaseDatabase-06dbb1f7d3c8a3e1.zip",
   "11.3.0": "https://dl.google.com/dl/firebase/ios/carthage/11.3.0/FirebaseDatabase-38634b55050b94fe.zip",
   "11.4.0": "https://dl.google.com/dl/firebase/ios/carthage/11.4.0/FirebaseDatabase-ed125984da534e96.zip",
+  "11.5.0": "https://dl.google.com/dl/firebase/ios/carthage/11.5.0/FirebaseDatabase-c31e803cad22c253.zip",
   "4.11.0": "https://dl.google.com/dl/firebase/ios/carthage/4.11.0/Database-1f7a820452722c7d.zip",
   "4.12.0": "https://dl.google.com/dl/firebase/ios/carthage/4.12.0/Database-1f7a820452722c7d.zip",
   "4.9.0": "https://dl.google.com/dl/firebase/ios/carthage/4.9.0/Database-59a12d87456b3e1c.zip",
diff --git a/ReleaseTooling/CarthageJSON/FirebaseDynamicLinksBinary.json b/ReleaseTooling/CarthageJSON/FirebaseDynamicLinksBinary.json
index adb21067b99..c4c50f91f6e 100644
--- a/ReleaseTooling/CarthageJSON/FirebaseDynamicLinksBinary.json
+++ b/ReleaseTooling/CarthageJSON/FirebaseDynamicLinksBinary.json
@@ -33,6 +33,7 @@
   "11.2.0": "https://dl.google.com/dl/firebase/ios/carthage/11.2.0/FirebaseDynamicLinks-e61c61fa80e5ea8a.zip",
   "11.3.0": "https://dl.google.com/dl/firebase/ios/carthage/11.3.0/FirebaseDynamicLinks-95f7e222d8456304.zip",
   "11.4.0": "https://dl.google.com/dl/firebase/ios/carthage/11.4.0/FirebaseDynamicLinks-f3f9d6cc60c8b832.zip",
+  "11.5.0": "https://dl.google.com/dl/firebase/ios/carthage/11.5.0/FirebaseDynamicLinks-2d21fc8dc1ab3b10.zip",
   "4.11.0": "https://dl.google.com/dl/firebase/ios/carthage/4.11.0/DynamicLinks-6a76740211df73f5.zip",
   "4.12.0": "https://dl.google.com/dl/firebase/ios/carthage/4.12.0/DynamicLinks-6a76740211df73f5.zip",
   "4.9.0": "https://dl.google.com/dl/firebase/ios/carthage/4.9.0/DynamicLinks-6a76740211df73f5.zip",
diff --git a/ReleaseTooling/CarthageJSON/FirebaseFirestoreBinary.json b/ReleaseTooling/CarthageJSON/FirebaseFirestoreBinary.json
index dc4e8e4c326..45a14e7f6e6 100644
--- a/ReleaseTooling/CarthageJSON/FirebaseFirestoreBinary.json
+++ b/ReleaseTooling/CarthageJSON/FirebaseFirestoreBinary.json
@@ -33,6 +33,7 @@
   "11.2.0": "https://dl.google.com/dl/firebase/ios/carthage/11.2.0/FirebaseFirestore-43af85b854ac842e.zip",
   "11.3.0": "https://dl.google.com/dl/firebase/ios/carthage/11.3.0/FirebaseFirestore-e1283f8cd2e0f3ec.zip",
   "11.4.0": "https://dl.google.com/dl/firebase/ios/carthage/11.4.0/FirebaseFirestore-f5864e67ddbbc9e8.zip",
+  "11.5.0": "https://dl.google.com/dl/firebase/ios/carthage/11.5.0/FirebaseFirestore-7cf86f9ac9b3545c.zip",
   "4.11.0": "https://dl.google.com/dl/firebase/ios/carthage/4.11.0/Firestore-68fc02c229d0cc69.zip",
   "4.12.0": "https://dl.google.com/dl/firebase/ios/carthage/4.12.0/Firestore-87a804ab561d91db.zip",
   "4.9.0": "https://dl.google.com/dl/firebase/ios/carthage/4.9.0/Firestore-ecb3eea7bde7e8e8.zip",
diff --git a/ReleaseTooling/CarthageJSON/FirebaseFunctionsBinary.json b/ReleaseTooling/CarthageJSON/FirebaseFunctionsBinary.json
index 456117effe1..efd2f26058d 100644
--- a/ReleaseTooling/CarthageJSON/FirebaseFunctionsBinary.json
+++ b/ReleaseTooling/CarthageJSON/FirebaseFunctionsBinary.json
@@ -33,6 +33,7 @@
   "11.2.0": "https://dl.google.com/dl/firebase/ios/carthage/11.2.0/FirebaseFunctions-307f00117c2efc62.zip",
   "11.3.0": "https://dl.google.com/dl/firebase/ios/carthage/11.3.0/FirebaseFunctions-02693a7583303912.zip",
   "11.4.0": "https://dl.google.com/dl/firebase/ios/carthage/11.4.0/FirebaseFunctions-8fce8623ed1c6b86.zip",
+  "11.5.0": "https://dl.google.com/dl/firebase/ios/carthage/11.5.0/FirebaseFunctions-367ecac87d727ede.zip",
   "4.11.0": "https://dl.google.com/dl/firebase/ios/carthage/4.11.0/Functions-f4c426016dd41e38.zip",
   "4.12.0": "https://dl.google.com/dl/firebase/ios/carthage/4.12.0/Functions-c6c44427c3034736.zip",
   "5.0.0": "https://dl.google.com/dl/firebase/ios/carthage/5.0.0/Functions-146f34c401bd459b.zip",
diff --git a/ReleaseTooling/CarthageJSON/FirebaseGoogleSignInBinary.json b/ReleaseTooling/CarthageJSON/FirebaseGoogleSignInBinary.json
index 8c45cdd1a76..e8fd8e45d64 100644
--- a/ReleaseTooling/CarthageJSON/FirebaseGoogleSignInBinary.json
+++ b/ReleaseTooling/CarthageJSON/FirebaseGoogleSignInBinary.json
@@ -33,6 +33,7 @@
   "11.2.0": "https://dl.google.com/dl/firebase/ios/carthage/11.2.0/GoogleSignIn-4e8837ef9594b57b.zip",
   "11.3.0": "https://dl.google.com/dl/firebase/ios/carthage/11.3.0/GoogleSignIn-8ce1c31ca2236212.zip",
   "11.4.0": "https://dl.google.com/dl/firebase/ios/carthage/11.4.0/GoogleSignIn-59eb371d148a2e3a.zip",
+  "11.5.0": "https://dl.google.com/dl/firebase/ios/carthage/11.5.0/GoogleSignIn-f7dcc2bce87fcb30.zip",
   "6.0.0": "https://dl.google.com/dl/firebase/ios/carthage/6.0.0/GoogleSignIn-de9c5d5e8eb6d6ea.zip",
   "6.1.0": "https://dl.google.com/dl/firebase/ios/carthage/6.1.0/GoogleSignIn-8c82f2870573a793.zip",
   "6.10.0": "https://dl.google.com/dl/firebase/ios/carthage/6.10.0/GoogleSignIn-ff3aef61c4a55b05.zip",
diff --git a/ReleaseTooling/CarthageJSON/FirebaseInAppMessagingBinary.json b/ReleaseTooling/CarthageJSON/FirebaseInAppMessagingBinary.json
index b7a994f8a62..13d04a0e6ea 100644
--- a/ReleaseTooling/CarthageJSON/FirebaseInAppMessagingBinary.json
+++ b/ReleaseTooling/CarthageJSON/FirebaseInAppMessagingBinary.json
@@ -33,6 +33,7 @@
   "11.2.0": "https://dl.google.com/dl/firebase/ios/carthage/11.2.0/FirebaseInAppMessaging-6fae0a778e9d3efa.zip",
   "11.3.0": "https://dl.google.com/dl/firebase/ios/carthage/11.3.0/FirebaseInAppMessaging-3a1a331c86520356.zip",
   "11.4.0": "https://dl.google.com/dl/firebase/ios/carthage/11.4.0/FirebaseInAppMessaging-a8054099dd2918b3.zip",
+  "11.5.0": "https://dl.google.com/dl/firebase/ios/carthage/11.5.0/FirebaseInAppMessaging-1264f987e42294c5.zip",
   "5.10.0": "https://dl.google.com/dl/firebase/ios/carthage/5.10.0/InAppMessaging-a7a3f933362f6e95.zip",
   "5.11.0": "https://dl.google.com/dl/firebase/ios/carthage/5.11.0/InAppMessaging-fa28ce1b88fbca93.zip",
   "5.12.0": "https://dl.google.com/dl/firebase/ios/carthage/5.12.0/InAppMessaging-fa28ce1b88fbca93.zip",
diff --git a/ReleaseTooling/CarthageJSON/FirebaseMLModelDownloaderBinary.json b/ReleaseTooling/CarthageJSON/FirebaseMLModelDownloaderBinary.json
index 6def9a51b34..93b98c740cd 100644
--- a/ReleaseTooling/CarthageJSON/FirebaseMLModelDownloaderBinary.json
+++ b/ReleaseTooling/CarthageJSON/FirebaseMLModelDownloaderBinary.json
@@ -33,6 +33,7 @@
   "11.2.0": "https://dl.google.com/dl/firebase/ios/carthage/11.2.0/FirebaseMLModelDownloader-d8649822e63fbf7f.zip",
   "11.3.0": "https://dl.google.com/dl/firebase/ios/carthage/11.3.0/FirebaseMLModelDownloader-517f51af92733a7f.zip",
   "11.4.0": "https://dl.google.com/dl/firebase/ios/carthage/11.4.0/FirebaseMLModelDownloader-069609cbcde7e789.zip",
+  "11.5.0": "https://dl.google.com/dl/firebase/ios/carthage/11.5.0/FirebaseMLModelDownloader-c6340805afa15d66.zip",
   "8.0.0": "https://dl.google.com/dl/firebase/ios/carthage/8.0.0/FirebaseMLModelDownloader-8f972757fb181320.zip",
   "8.1.0": "https://dl.google.com/dl/firebase/ios/carthage/8.1.0/FirebaseMLModelDownloader-058ad59fa6dc0111.zip",
   "8.10.0": "https://dl.google.com/dl/firebase/ios/carthage/8.10.0/FirebaseMLModelDownloader-286479a966d2fb37.zip",
diff --git a/ReleaseTooling/CarthageJSON/FirebaseMessagingBinary.json b/ReleaseTooling/CarthageJSON/FirebaseMessagingBinary.json
index 9bdf4b5b932..02aa108e989 100644
--- a/ReleaseTooling/CarthageJSON/FirebaseMessagingBinary.json
+++ b/ReleaseTooling/CarthageJSON/FirebaseMessagingBinary.json
@@ -33,6 +33,7 @@
   "11.2.0": "https://dl.google.com/dl/firebase/ios/carthage/11.2.0/FirebaseMessaging-70e63bb9d9590ded.zip",
   "11.3.0": "https://dl.google.com/dl/firebase/ios/carthage/11.3.0/FirebaseMessaging-8a39834fead3c581.zip",
   "11.4.0": "https://dl.google.com/dl/firebase/ios/carthage/11.4.0/FirebaseMessaging-2d09725e8b98d199.zip",
+  "11.5.0": "https://dl.google.com/dl/firebase/ios/carthage/11.5.0/FirebaseMessaging-984ae5d3101abc86.zip",
   "4.11.0": "https://dl.google.com/dl/firebase/ios/carthage/4.11.0/Messaging-a22ef2b5f2f30f82.zip",
   "4.12.0": "https://dl.google.com/dl/firebase/ios/carthage/4.12.0/Messaging-94fa4e090c7e9185.zip",
   "4.9.0": "https://dl.google.com/dl/firebase/ios/carthage/4.9.0/Messaging-2a00a1c64a19d176.zip",
diff --git a/ReleaseTooling/CarthageJSON/FirebasePerformanceBinary.json b/ReleaseTooling/CarthageJSON/FirebasePerformanceBinary.json
index 666b7238816..ed98e7ed341 100644
--- a/ReleaseTooling/CarthageJSON/FirebasePerformanceBinary.json
+++ b/ReleaseTooling/CarthageJSON/FirebasePerformanceBinary.json
@@ -33,6 +33,7 @@
   "11.2.0": "https://dl.google.com/dl/firebase/ios/carthage/11.2.0/FirebasePerformance-aa174ee3102722d9.zip",
   "11.3.0": "https://dl.google.com/dl/firebase/ios/carthage/11.3.0/FirebasePerformance-a489ac7a27d9b53d.zip",
   "11.4.0": "https://dl.google.com/dl/firebase/ios/carthage/11.4.0/FirebasePerformance-9a6f62e80c2324f4.zip",
+  "11.5.0": "https://dl.google.com/dl/firebase/ios/carthage/11.5.0/FirebasePerformance-28996619a5fdc4b7.zip",
   "4.11.0": "https://dl.google.com/dl/firebase/ios/carthage/4.11.0/Performance-d8693eb892bfa05b.zip",
   "4.12.0": "https://dl.google.com/dl/firebase/ios/carthage/4.12.0/Performance-0a400f9460f7a71d.zip",
   "4.9.0": "https://dl.google.com/dl/firebase/ios/carthage/4.9.0/Performance-f5b4002ab96523e4.zip",
diff --git a/ReleaseTooling/CarthageJSON/FirebaseRemoteConfigBinary.json b/ReleaseTooling/CarthageJSON/FirebaseRemoteConfigBinary.json
index f6e8410b08b..e00f9946e4d 100644
--- a/ReleaseTooling/CarthageJSON/FirebaseRemoteConfigBinary.json
+++ b/ReleaseTooling/CarthageJSON/FirebaseRemoteConfigBinary.json
@@ -33,6 +33,7 @@
   "11.2.0": "https://dl.google.com/dl/firebase/ios/carthage/11.2.0/FirebaseRemoteConfig-9a298869ce3cc6db.zip",
   "11.3.0": "https://dl.google.com/dl/firebase/ios/carthage/11.3.0/FirebaseRemoteConfig-940ed38696414882.zip",
   "11.4.0": "https://dl.google.com/dl/firebase/ios/carthage/11.4.0/FirebaseRemoteConfig-ec432e976582d0eb.zip",
+  "11.5.0": "https://dl.google.com/dl/firebase/ios/carthage/11.5.0/FirebaseRemoteConfig-672acb139b4848ef.zip",
   "4.11.0": "https://dl.google.com/dl/firebase/ios/carthage/4.11.0/RemoteConfig-7e9635365ccd4a17.zip",
   "4.12.0": "https://dl.google.com/dl/firebase/ios/carthage/4.12.0/RemoteConfig-e7928fcb6311c439.zip",
   "4.9.0": "https://dl.google.com/dl/firebase/ios/carthage/4.9.0/RemoteConfig-9ab1ca5f360a1780.zip",
diff --git a/ReleaseTooling/CarthageJSON/FirebaseStorageBinary.json b/ReleaseTooling/CarthageJSON/FirebaseStorageBinary.json
index 46f2d604ad5..b5a9246e76e 100644
--- a/ReleaseTooling/CarthageJSON/FirebaseStorageBinary.json
+++ b/ReleaseTooling/CarthageJSON/FirebaseStorageBinary.json
@@ -33,6 +33,7 @@
   "11.2.0": "https://dl.google.com/dl/firebase/ios/carthage/11.2.0/FirebaseStorage-b9b969b0d1254065.zip",
   "11.3.0": "https://dl.google.com/dl/firebase/ios/carthage/11.3.0/FirebaseStorage-0435eeaa87324cd4.zip",
   "11.4.0": "https://dl.google.com/dl/firebase/ios/carthage/11.4.0/FirebaseStorage-0b7a2306152984a2.zip",
+  "11.5.0": "https://dl.google.com/dl/firebase/ios/carthage/11.5.0/FirebaseStorage-a1f0f159f3d7072b.zip",
   "4.11.0": "https://dl.google.com/dl/firebase/ios/carthage/4.11.0/Storage-6b3e77e1a7fdbc61.zip",
   "4.12.0": "https://dl.google.com/dl/firebase/ios/carthage/4.12.0/Storage-4721c35d2b90a569.zip",
   "4.9.0": "https://dl.google.com/dl/firebase/ios/carthage/4.9.0/Storage-821299369b9d0fb2.zip",
diff --git a/ReleaseTooling/CarthageJSON/FirebaseVertexAIBinary.json b/ReleaseTooling/CarthageJSON/FirebaseVertexAIBinary.json
index 0967ef424bc..6f3fcd57470 100644
--- a/ReleaseTooling/CarthageJSON/FirebaseVertexAIBinary.json
+++ b/ReleaseTooling/CarthageJSON/FirebaseVertexAIBinary.json
@@ -1 +1,3 @@
-{}
+{
+  "11.5.0": "https://dl.google.com/dl/firebase/ios/carthage/11.5.0/FirebaseVertexAI-d5d0ffd8010245da.zip"
+}
diff --git a/ReleaseTooling/Sources/FirebaseManifest/FirebaseManifest.swift b/ReleaseTooling/Sources/FirebaseManifest/FirebaseManifest.swift
index 17d32d4c985..bf28d99c158 100755
--- a/ReleaseTooling/Sources/FirebaseManifest/FirebaseManifest.swift
+++ b/ReleaseTooling/Sources/FirebaseManifest/FirebaseManifest.swift
@@ -21,7 +21,7 @@ import Foundation
 /// The version and releasing fields of the non-Firebase pods should be reviewed every release.
 /// The array should be ordered so that any pod's dependencies precede it in the list.
 public let shared = Manifest(
-  version: "11.5.0",
+  version: "11.6.0",
   pods: [
     Pod("FirebaseSharedSwift"),
     Pod("FirebaseCoreInternal"),
@@ -55,6 +55,7 @@ public let shared = Manifest(
     Pod("FirebaseMLModelDownloader", isBeta: true, zip: true),
     Pod("FirebaseVertexAI", zip: true),
     Pod("Firebase", allowWarnings: true, platforms: ["ios", "tvos", "macos"], zip: true),
+    Pod("FirebaseCombineSwift", releasing: false, zip: false),
   ]
 )
 
@@ -64,6 +65,7 @@ public struct Manifest {
   public let pods: [Pod]
 
   public func versionString(_ pod: Pod) -> String {
+    let version = pod.podVersion ?? self.version
     return pod.isBeta ? version + "-beta" : version
   }
 }
diff --git a/ReleaseTooling/Sources/FirebaseManifest/Pod.swift b/ReleaseTooling/Sources/FirebaseManifest/Pod.swift
index ca11ba35b23..0bb5c19a208 100755
--- a/ReleaseTooling/Sources/FirebaseManifest/Pod.swift
+++ b/ReleaseTooling/Sources/FirebaseManifest/Pod.swift
@@ -28,6 +28,8 @@ public struct Pod {
   public let allowWarnings: Bool
   /// Set of platforms (e.g. "ios", "macos", "tvos", or "watchos") to build this pod for.
   public let platforms: Set<String>
+  /// Allows overriding the ``Manifest/version`` for this pod; defaults to `nil`.
+  public let podVersion: String?
   /// Whether or not the pod is planned for publicly releasing (as some pods are for
   /// internal/testing use).
   public let releasing: Bool
@@ -47,6 +49,7 @@ public struct Pod {
     self.isBeta = isBeta
     self.allowWarnings = allowWarnings
     self.platforms = platforms
+    self.podVersion = podVersion
     self.releasing = releasing
     self.zip = zip
   }
diff --git a/ReleaseTooling/Sources/ZipBuilder/ZipBuilder.swift b/ReleaseTooling/Sources/ZipBuilder/ZipBuilder.swift
index 992ed2e9d89..d19cd4c32e5 100644
--- a/ReleaseTooling/Sources/ZipBuilder/ZipBuilder.swift
+++ b/ReleaseTooling/Sources/ZipBuilder/ZipBuilder.swift
@@ -361,7 +361,7 @@ struct ZipBuilder {
   /// - Throws: One of many errors that could have happened during the build phase.
   func buildAndAssembleFirebaseRelease(templateDir: URL) throws -> ReleaseArtifacts {
     let manifest = FirebaseManifest.shared
-    var podsToInstall = manifest.pods.map {
+    var podsToInstall = manifest.pods.filter { $0.releasing }.map {
       CocoaPodUtils.VersionedPod(name: $0.name,
                                  version: manifest.versionString($0),
                                  platforms: $0.platforms)
diff --git a/scripts/zip_quickstart_test.sh b/scripts/zip_quickstart_test.sh
index 3fb13ebac88..3b531f8e3f9 100755
--- a/scripts/zip_quickstart_test.sh
+++ b/scripts/zip_quickstart_test.sh
@@ -30,11 +30,23 @@ if [[ ! -z "$LEGACY" ]]; then
   cd "Legacy${SAMPLE}Quickstart"
 fi
 
+xcode_version=$(xcodebuild -version | grep Xcode)
+xcode_version="${xcode_version/Xcode /}"
+xcode_major="${xcode_version/.*/}"
+
+if [[ "$xcode_major" -lt 15 ]]; then
+  device_name="iPhone 14"
+elif [[ "$xcode_major" -lt 16 ]]; then
+  device_name="iPhone 15"
+else
+  device_name="iPhone 16"
+fi
+
 (
 xcodebuild \
 -project ${SAMPLE}Example.xcodeproj \
 -scheme  ${SAMPLE}Example${SWIFT_SUFFIX} \
--destination 'platform=iOS Simulator,name=iPhone 14' "SWIFT_VERSION=5.3" "OTHER_LDFLAGS=\$(OTHER_LDFLAGS) -ObjC" "FRAMEWORK_SEARCH_PATHS= \$(PROJECT_DIR)/Firebase/" HEADER_SEARCH_PATHS='$(PROJECT_DIR)/Firebase' \
+-destination "platform=iOS Simulator,name=$device_name" "SWIFT_VERSION=5.3" "OTHER_LDFLAGS=\$(OTHER_LDFLAGS) -ObjC" "FRAMEWORK_SEARCH_PATHS= \$(PROJECT_DIR)/Firebase/" HEADER_SEARCH_PATHS='$(PROJECT_DIR)/Firebase' \
 build \
 ) || EXIT_STATUS=$?