diff --git a/.env b/.env
index 4aec14e7..88359ed6 100644
--- a/.env
+++ b/.env
@@ -35,7 +35,7 @@ ROLLBAR_POST_CLIENT_ITEM_TOKEN=""
 GITLAB_APP_ID=
 GITLAB_APP_SECRET=
 GITLAB_REDIRECT_URI=
-GITLAB_API_ENDPOINT=
+GITLAB_API_ENDPOINT="https://gitlab.com/api/v4"
 GITLAB_WEBHOOK_SECRET=
 GITLAB_DEPLOYQA_BOT_ID=
 GITLAB_DEPLOYQA_BOT_TOKEN=
diff --git a/app/controllers/sessions_controller.rb b/app/controllers/sessions_controller.rb
index 3ee3a00a..e9a6ba7a 100644
--- a/app/controllers/sessions_controller.rb
+++ b/app/controllers/sessions_controller.rb
@@ -7,14 +7,14 @@ class SessionsController < ApplicationController
   def show; end
 
   def create
-    result = user_from_omniauth
+    result = current_user ? connect_user : user_from_omniauth
 
     if result.error?
       flash.notice = result.errors.join("/n")
       return redirect_to sessions_path
     end
 
-    setup_session(request.session, result.object)
+    setup_session(result.object)
     redirect_to projects_path
   end
 
@@ -25,8 +25,14 @@ def destroy
 
   protected
 
-  def setup_session(session, user)
-    ::Auth::SessionHandler.new(session).set!(user_id: user.id, provider: auth_info_presenter.provider)
+  def setup_session(user)
+    return if current_user
+
+    ::Auth::SessionHandler.new(request.session).set!(user_id: user.id, provider: auth_info_presenter.provider)
+  end
+
+  def connect_user
+    Auth::AnotherServiceConnection.new(auth_info_presenter, current_user).call
   end
 
   def user_from_omniauth
diff --git a/app/controllers/users_controller.rb b/app/controllers/users_controller.rb
new file mode 100644
index 00000000..9ca41239
--- /dev/null
+++ b/app/controllers/users_controller.rb
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+class UsersController < ApplicationController
+  def show
+    @user = find_user
+    @github_auth = @user.user_references.find { |reference| reference.auth_provider == OmniauthConstants::GITHUB }
+    @gitlab_auth = @user.user_references.find { |reference| reference.auth_provider == OmniauthConstants::GITLAB }
+  end
+
+  private
+
+  def find_user
+    authorize User.includes(user_references: :auth_info).find(params[:id]), :show?, policy_class: UserPolicy
+  end
+end
diff --git a/app/models/user_reference.rb b/app/models/user_reference.rb
index b3d53b9f..9213fdde 100644
--- a/app/models/user_reference.rb
+++ b/app/models/user_reference.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 class UserReference < ApplicationRecord
-  belongs_to :user, dependent: :destroy, required: false
+  belongs_to :user, required: false
   has_one :auth_info, dependent: :destroy
 
   validates :full_name, :auth_uid, :auth_provider, presence: true
diff --git a/app/policies/user_policy.rb b/app/policies/user_policy.rb
new file mode 100644
index 00000000..1c3332aa
--- /dev/null
+++ b/app/policies/user_policy.rb
@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+class UserPolicy < ApplicationPolicy
+  def show?
+    return true if user.system_role == UserConstants::SystemRoles::ADMIN
+
+    user.actual_user == record
+  end
+end
diff --git a/app/services/auth/accessibility_check.rb b/app/services/auth/accessibility_check.rb
index 2777980c..cc33af58 100644
--- a/app/services/auth/accessibility_check.rb
+++ b/app/services/auth/accessibility_check.rb
@@ -7,16 +7,33 @@ def initialize(user_reference, email)
       @email = email
     end
 
-    def call
+    def ensure_user_doesnt_exists!
       raise ::Auth::NotPermittedError, "User already exists" if @user_reference.blank? && auth_info_email_occupied?
+    end
 
+    def ensure_reference_is_not_secondary!
       return if @user_reference.blank?
       return if @user_reference.auth_info.blank?
       return if @user_reference.auth_info.primary?
 
-      raise ::Auth::NotPermittedError, "Please login with another provider"
+      raise ::Auth::NotPermittedError, "You've already registered in another provider with the same email"
+    end
+
+    def ensure_reference_is_not_connected!
+      return if @user_reference.blank?
+      return if @user_reference.auth_info.blank? && @user_reference.user_id.blank?
+
+      raise ::Auth::NotPermittedError, "New account is already registered in system"
     end
 
+    def ensure_email_is_the_same!(current_user)
+      return if current_user.auth_info.email == @email
+
+      raise ::Auth::NotPermittedError, "Your email '#{@email}' doesn't match with your account's email '#{current_user.auth_info.email}'"
+    end
+
+    private
+
     def auth_info_email_occupied?
       AuthInfo.find_by(email: @email).present?
     end
diff --git a/app/services/auth/another_service_connection.rb b/app/services/auth/another_service_connection.rb
new file mode 100644
index 00000000..a509886f
--- /dev/null
+++ b/app/services/auth/another_service_connection.rb
@@ -0,0 +1,51 @@
+# frozen_string_literal: true
+
+module Auth
+  class AnotherServiceConnection
+    def initialize(auth_info_presenter, current_user)
+      @auth_info_presenter = auth_info_presenter
+      @current_user = current_user
+    end
+
+    def call
+      user_reference = UserReference.find_by(auth_uid: @auth_info_presenter.uid, auth_provider: @auth_info_presenter.provider)
+      ensure_user_is_ready!(user_reference)
+
+      ActiveRecord::Base.transaction do
+        user_reference = user_reference.present? ? update_reference(user_reference) : create_reference
+        create_auth_info(user_reference)
+      end
+
+      ReturnValue.ok(@current_user.actual_user)
+    rescue ::Auth::NotPermittedError => error
+      ReturnValue.error(errors: error.message)
+    end
+
+    private
+
+    def ensure_user_is_ready!(user_reference)
+      checker = Auth::AccessibilityCheck.new(user_reference, @auth_info_presenter.email)
+      checker.ensure_reference_is_not_connected!
+      checker.ensure_email_is_the_same!(@current_user)
+    end
+
+    def update_reference(user_reference)
+      user_reference.update!(user: @current_user.actual_user)
+      user_reference
+    end
+
+    def create_reference
+      UserReference.create!(
+        user: @current_user.actual_user,
+        auth_uid: @auth_info_presenter.uid,
+        auth_provider: @auth_info_presenter.provider,
+        full_name: @auth_info_presenter.full_name
+      )
+    end
+
+    def create_auth_info(user_reference)
+      auth_info_params = Auth::AuthInfoParamsBuilder.new(@auth_info_presenter, user_reference).call
+      AuthInfo.create!(auth_info_params)
+    end
+  end
+end
diff --git a/app/services/auth/auth_info_params_builder.rb b/app/services/auth/auth_info_params_builder.rb
index c21434e5..d3bbff16 100644
--- a/app/services/auth/auth_info_params_builder.rb
+++ b/app/services/auth/auth_info_params_builder.rb
@@ -24,8 +24,9 @@ def call
     def load_email(params)
       return if params[:email].present?
 
+      # TODO: why do we need USER_API_CLIENT? GitLab always have an email and there is no :email method in ProviderAPI::Gitlab::UserClient
       api_client = USER_API_CLIENT.fetch(@omniauth_info_presenter.provider).new(@omniauth_info_presenter.token)
-      email = api_client.emails.find { |email_info| email_info[:primary] }.fetch(:email)
+      email = api_client.emails.find { |email_info| email_info[:primary] }[:email]
       params[:email] = email
     end
   end
diff --git a/app/services/auth/user_authenticator.rb b/app/services/auth/user_authenticator.rb
index 97c48c75..273d7ecc 100644
--- a/app/services/auth/user_authenticator.rb
+++ b/app/services/auth/user_authenticator.rb
@@ -4,10 +4,12 @@ module Auth
   class UserAuthenticator
     def initialize(auth_info_presenter)
       @auth_info_presenter = auth_info_presenter
+      @checker = Auth::AccessibilityCheck.new(user_reference, @auth_info_presenter.email)
     end
 
     def call
-      Auth::AccessibilityCheck.new(user_reference, @auth_info_presenter.email).call
+      @checker.ensure_user_doesnt_exists!
+      @checker.ensure_reference_is_not_secondary!
 
       if user_reference.blank?
         ::Auth::UserCreator.new(@auth_info_presenter).call
diff --git a/app/services/auth/user_wrapper.rb b/app/services/auth/user_wrapper.rb
index 0367b026..7c24ba78 100644
--- a/app/services/auth/user_wrapper.rb
+++ b/app/services/auth/user_wrapper.rb
@@ -24,5 +24,9 @@ def email
     def token
       auth_info.token
     end
+
+    def actual_user
+      @user
+    end
   end
 end
diff --git a/app/views/layouts/_header.html.slim b/app/views/layouts/_header.html.slim
index 415e32ae..2d3299a5 100644
--- a/app/views/layouts/_header.html.slim
+++ b/app/views/layouts/_header.html.slim
@@ -10,4 +10,5 @@ nav.navbar.navbar-expand-lg.navbar-light.bg-light
         a.nav-link.dropdown-toggle href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false"
           = current_user.full_name
         .dropdown-menu aria-labelledby="navbarDropdown"
+          = link_to "User preferences", user_path(current_user.actual_user), class: "dropdown-item"
           = link_to "Log out", sessions_path, method: :delete, class: "dropdown-item"
diff --git a/app/views/users/show.html.slim b/app/views/users/show.html.slim
new file mode 100644
index 00000000..41be1903
--- /dev/null
+++ b/app/views/users/show.html.slim
@@ -0,0 +1,23 @@
+.container
+  = render partial: "shared/breadcrumb", locals: {\
+      text_link_hash: {\
+        "User" => nil\
+      },
+      class: "mt-4" }
+
+
+  .d-flex.justify-content-between.mt-4
+    h1 = current_user.full_name
+  .mt-4
+    p
+      = image_pack_tag("media/images/logos/github-logo.svg", size: "32x32", class: "mr-2")
+      - if @github_auth.present?
+        span.text-success Github integration connected!
+      - else
+        = link_to "Click to connect Github", omniauth_path("github"), method: :post
+    p
+      = image_pack_tag("media/images/logos/gitlab-logo.svg", size: "32x32", class: "mr-2")
+      - if @gitlab_auth.present?
+        span.text-success Gitlab integration connected!
+      - else
+        = link_to "Click to connect Gitlab", omniauth_path("gitlab", some_data: "123"), method: :post
diff --git a/config/routes.rb b/config/routes.rb
index 6e63376f..603e657f 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -12,13 +12,14 @@
   get "/auth/slack/callback", to: "slack/authentications#create"
   get "/auth/failure", to: "slack/authentications#show"
   get "/auth/:provider/callback", to: "sessions#create"
-  get "/auth/:provider", to: "sessions#show", as: "omniauth"
+  post "/auth/:provider", to: "sessions#show", as: "omniauth"
 
   constraints Routes::LoggedUserConstraint.new(SidekiqPolicy) do
     mount Sidekiq::Web => "/sidekiq"
   end
 
   resource :sessions, only: %i[show create destroy]
+  resources :users, only: %i[show]
 
   namespace :webhooks do
     resources :github, only: %i[create]