diff --git a/pkgs/by-name/ad/ada-url/conditional-dl.patch b/pkgs/by-name/ad/ada-url/conditional-dl.patch
new file mode 100644
index 0000000000000..8c62b073ba67c
--- /dev/null
+++ b/pkgs/by-name/ad/ada-url/conditional-dl.patch
@@ -0,0 +1,20 @@
+diff --git a/cmake/CPM.cmake b/cmake/CPM.cmake
+index ad6b74a8..079eed46 100644
+--- a/cmake/CPM.cmake
++++ b/cmake/CPM.cmake
+@@ -16,9 +16,11 @@ endif()
+ # Expand relative path. This is important if the provided path contains a tilde (~)
+ get_filename_component(CPM_DOWNLOAD_LOCATION ${CPM_DOWNLOAD_LOCATION} ABSOLUTE)
+ 
+-file(DOWNLOAD
+-     https://github.com/cpm-cmake/CPM.cmake/releases/download/v${CPM_DOWNLOAD_VERSION}/CPM.cmake
+-     ${CPM_DOWNLOAD_LOCATION} EXPECTED_HASH SHA256=${CPM_HASH_SUM}
+-)
++if(NOT (EXISTS ${CPM_DOWNLOAD_LOCATION}))
++  file(DOWNLOAD
++       https://github.com/cpm-cmake/CPM.cmake/releases/download/v${CPM_DOWNLOAD_VERSION}/CPM.cmake
++       ${CPM_DOWNLOAD_LOCATION} EXPECTED_HASH SHA256=${CPM_HASH_SUM}
++  )
++endif()
+ 
+ include(${CPM_DOWNLOAD_LOCATION})
diff --git a/pkgs/by-name/ad/ada-url/package.nix b/pkgs/by-name/ad/ada-url/package.nix
new file mode 100644
index 0000000000000..5d366873eca70
--- /dev/null
+++ b/pkgs/by-name/ad/ada-url/package.nix
@@ -0,0 +1,61 @@
+{
+  lib,
+  fetchFromGitHub,
+  stdenv,
+  cpm-cmake,
+  simdjson,
+  cmake,
+  cxxopts,
+}:
+
+let
+  googletest = fetchFromGitHub {
+    owner = "google";
+    repo = "googletest";
+    rev = "v1.14.0";
+    hash = "sha256-t0RchAHTJbuI5YW4uyBPykTvcjy90JW9AOPNjIhwh6U=";
+  };
+  googlebenchmark = fetchFromGitHub {
+    owner = "google";
+    repo = "benchmark";
+    rev = "v1.6.0";
+    hash = "sha256-EAJk3JhLdkuGKRMtspTLejck8doWPd7Z0Lv/Mvf3KFY=";
+  };
+  pname = "ada";
+  version = "2.7.7";
+in
+stdenv.mkDerivation rec {
+  inherit pname version;
+  src = fetchFromGitHub {
+    owner = "ada-url";
+    repo = pname;
+    rev = "v${version}";
+    hash = "sha256-eh/tOwU+sU/8FYYuRE7DL1v1Fp6bNFWneLtGG0wsWgA=";
+  };
+
+  patches = [ ./conditional-dl.patch ];
+
+  preConfigure = ''
+    mkdir -p ${placeholder "out"}/share/cpm
+    cp ${cpm-cmake}/share/cpm/CPM.cmake ${placeholder "out"}/share/cpm/CPM_0.38.6.cmake
+  '';
+
+  cmakeFlags = [
+    "-DCPM_SOURCE_CACHE=${placeholder "out"}/share"
+    "-DFETCHCONTENT_SOURCE_DIR_SIMDJSON=${simdjson.src}"
+    "-DFETCHCONTENT_SOURCE_DIR_GTEST=${googletest}"
+    "-DFETCHCONTENT_SOURCE_DIR_BENCHMARK=${googlebenchmark}"
+    "-DBUILD_SHARED_LIBS=ON"
+  ];
+
+  nativeBuildInputs = [ cmake ];
+
+  buildInputs = [ cxxopts ];
+  meta = with lib; {
+    homepage = "https://www.ada-url.com/";
+    description = "WHATWG-compliant and fast URL parser written in modern C++";
+    license = licenses.asl20;
+    platforms = [ "x86_64-linux" ];
+    maintainers = with maintainers; [ genevieve-me ];
+  };
+}