diff --git a/CHANGELOG.md b/CHANGELOG.md
index b69a3e32..993af968 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,17 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## Unreleased
 
+# OIDC and KML support release
+
+To configure your OIDC provider, set the following environment variables:
+
+```
+OIDC_CLIENT_ID=client_id_example
+OIDC_CLIENT_SECRET=client_secret_example
+OIDC_ISSUER=https://authentik.yourdomain.com/application/o/dawarich/
+OIDC_REDIRECT_URI=https://your-dawarich-url.com/users/auth/openid_connect/callback
+```
+
 ## Added
 
 - Support for KML file uploads. #350
@@ -18,6 +29,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ## Changed
 
 - Internal redis settings updated to implement support for connecting to Redis via unix socket. #1706
+- Implemented authentication via GitHub and Google for Dawarich Cloud.
+- Implemented OpenID Connect authentication for self-hosted Dawarich instances. #66
+
 
 # [0.35.1] - 2025-11-09
 
diff --git a/Gemfile b/Gemfile
index e1817622..36cf0d9c 100644
--- a/Gemfile
+++ b/Gemfile
@@ -5,7 +5,7 @@ git_source(:github) { |repo| "https://github.com/#{repo}.git" }
 
 ruby File.read('.ruby-version').strip
 
-gem 'activerecord-postgis-adapter', '~> 11.0'
+gem 'activerecord-postgis-adapter', '11.0'
 # https://meta.discourse.org/t/cant-rebuild-due-to-aws-sdk-gem-bump-and-new-aws-data-integrity-protections/354217/40
 gem 'aws-sdk-core', '~> 3.215.1', require: false
 gem 'aws-sdk-kms', '~> 1.96.0', require: false
@@ -24,6 +24,10 @@ gem 'jwt', '~> 2.8'
 gem 'kaminari'
 gem 'lograge'
 gem 'oj'
+gem 'omniauth-github', '~> 2.0.0'
+gem 'omniauth-google-oauth2'
+gem 'omniauth_openid_connect'
+gem 'omniauth-rails_csrf_protection'
 gem 'parallel'
 gem 'pg'
 gem 'prometheus_exporter'
diff --git a/Gemfile.lock b/Gemfile.lock
index bcf42c11..a32eb801 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -86,8 +86,10 @@ GEM
       uri (>= 0.13.1)
     addressable (2.8.7)
       public_suffix (>= 2.0.2, < 7.0)
+    aes_key_wrap (1.1.0)
     ast (2.4.3)
     attr_extras (7.1.0)
+    attr_required (1.0.2)
     aws-eventstream (1.3.2)
     aws-partitions (1.1072.0)
     aws-sdk-core (3.215.1)
@@ -108,6 +110,7 @@ GEM
     bcrypt (3.1.20)
     benchmark (0.4.1)
     bigdecimal (3.3.1)
+    bindata (2.5.1)
     bootsnap (1.18.6)
       msgpack (~> 1.2)
     brakeman (7.1.0)
@@ -161,6 +164,8 @@ GEM
       dotenv (= 3.1.8)
       railties (>= 6.1)
     drb (2.2.3)
+    email_validator (2.2.4)
+      activemodel
     erb (5.1.3)
     erubi (1.13.1)
     et-orbi (1.4.0)
@@ -171,6 +176,14 @@ GEM
       factory_bot (~> 6.5)
       railties (>= 6.1.0)
     fakeredis (0.1.4)
+    faraday (2.14.0)
+      faraday-net_http (>= 2.0, < 3.5)
+      json
+      logger
+    faraday-follow_redirects (0.4.0)
+      faraday (>= 1, < 3)
+    faraday-net_http (3.4.1)
+      net-http (>= 0.5.0)
     ffaker (2.25.0)
     ffi (1.17.2-aarch64-linux-gnu)
     ffi (1.17.2-arm-linux-gnu)
@@ -196,6 +209,7 @@ GEM
       rgeo-geojson (~> 2.1)
       zeitwerk (~> 2.5)
     hashdiff (1.1.2)
+    hashie (5.0.0)
     httparty (0.23.1)
       csv
       mini_mime (>= 1.0.0)
@@ -213,6 +227,13 @@ GEM
       reline (>= 0.4.2)
     jmespath (1.6.2)
     json (2.15.0)
+    json-jwt (1.17.0)
+      activesupport (>= 4.2)
+      aes_key_wrap
+      base64
+      bindata
+      faraday (~> 2.0)
+      faraday-follow_redirects
     json-schema (5.0.1)
       addressable (~> 2.8)
     jwt (2.10.1)
@@ -256,6 +277,8 @@ GEM
     multi_json (1.15.0)
     multi_xml (0.7.1)
       bigdecimal (~> 3.1)
+    net-http (0.6.0)
+      uri
     net-imap (0.5.12)
       date
       net-protocol
@@ -279,9 +302,52 @@ GEM
       racc (~> 1.4)
     nokogiri (1.18.10-x86_64-linux-gnu)
       racc (~> 1.4)
+    oauth2 (2.0.17)
+      faraday (>= 0.17.3, < 4.0)
+      jwt (>= 1.0, < 4.0)
+      logger (~> 1.2)
+      multi_xml (~> 0.5)
+      rack (>= 1.2, < 4)
+      snaky_hash (~> 2.0, >= 2.0.3)
+      version_gem (~> 1.1, >= 1.1.9)
     oj (3.16.11)
       bigdecimal (>= 3.0)
       ostruct (>= 0.2)
+    omniauth (2.1.4)
+      hashie (>= 3.4.6)
+      logger
+      rack (>= 2.2.3)
+      rack-protection
+    omniauth-github (2.0.1)
+      omniauth (~> 2.0)
+      omniauth-oauth2 (~> 1.8)
+    omniauth-google-oauth2 (1.2.1)
+      jwt (>= 2.9.2)
+      oauth2 (~> 2.0)
+      omniauth (~> 2.0)
+      omniauth-oauth2 (~> 1.8)
+    omniauth-oauth2 (1.8.0)
+      oauth2 (>= 1.4, < 3)
+      omniauth (~> 2.0)
+    omniauth-rails_csrf_protection (1.0.2)
+      actionpack (>= 4.2)
+      omniauth (~> 2.0)
+    omniauth_openid_connect (0.8.0)
+      omniauth (>= 1.9, < 3)
+      openid_connect (~> 2.2)
+    openid_connect (2.3.1)
+      activemodel
+      attr_required (>= 1.0.0)
+      email_validator
+      faraday (~> 2.0)
+      faraday-follow_redirects
+      json-jwt (>= 1.16)
+      mail
+      rack-oauth2 (~> 2.2)
+      swd (~> 2.0)
+      tzinfo
+      validate_url
+      webfinger (~> 2.0)
     optimist (3.2.1)
     orm_adapter (0.5.0)
     ostruct (0.6.1)
@@ -321,6 +387,17 @@ GEM
     raabro (1.4.0)
     racc (1.8.1)
     rack (3.2.3)
+    rack-oauth2 (2.3.0)
+      activesupport
+      attr_required
+      faraday (~> 2.0)
+      faraday-follow_redirects
+      json-jwt (>= 1.11.0)
+      rack (>= 2.1.0)
+    rack-protection (4.2.1)
+      base64 (>= 0.1.0)
+      logger (>= 1.6.0)
+      rack (>= 3.0.0, < 4)
     rack-session (2.1.1)
       base64 (>= 0.1.0)
       rack (>= 3.0.0)
@@ -475,6 +552,9 @@ GEM
       simplecov_json_formatter (~> 0.1)
     simplecov-html (0.13.1)
     simplecov_json_formatter (0.1.4)
+    snaky_hash (2.0.3)
+      hashie (>= 0.1.0, < 6)
+      version_gem (>= 1.1.8, < 3)
     sprockets (4.2.1)
       concurrent-ruby (~> 1.0)
       rack (>= 2.2.4, < 4)
@@ -492,6 +572,11 @@ GEM
       attr_extras (>= 6.2.4)
       diff-lcs
       patience_diff
+    swd (2.0.3)
+      activesupport (>= 3)
+      attr_required (>= 0.0.5)
+      faraday (~> 2.0)
+      faraday-follow_redirects
     tailwindcss-rails (3.3.2)
       railties (>= 7.0.0)
       tailwindcss-ruby (~> 3.0)
@@ -515,8 +600,16 @@ GEM
     unicode-emoji (4.1.0)
     uri (1.0.4)
     useragent (0.16.11)
+    validate_url (1.0.15)
+      activemodel (>= 3.0.0)
+      public_suffix
+    version_gem (1.1.9)
     warden (1.2.9)
       rack (>= 2.0.9)
+    webfinger (2.1.3)
+      activesupport
+      faraday (~> 2.0)
+      faraday-follow_redirects
     webmock (3.25.1)
       addressable (>= 2.8.0)
       crack (>= 0.3.2)
@@ -540,7 +633,7 @@ PLATFORMS
   x86_64-linux
 
 DEPENDENCIES
-  activerecord-postgis-adapter (~> 11.0)
+  activerecord-postgis-adapter (= 11.0)
   aws-sdk-core (~> 3.215.1)
   aws-sdk-kms (~> 1.96.0)
   aws-sdk-s3 (~> 1.177.0)
@@ -568,6 +661,10 @@ DEPENDENCIES
   kaminari
   lograge
   oj
+  omniauth-github (~> 2.0.0)
+  omniauth-google-oauth2
+  omniauth-rails_csrf_protection
+  omniauth_openid_connect
   parallel
   pg
   prometheus_exporter
diff --git a/app/controllers/users/omniauth_callbacks_controller.rb b/app/controllers/users/omniauth_callbacks_controller.rb
new file mode 100644
index 00000000..10fd37ac
--- /dev/null
+++ b/app/controllers/users/omniauth_callbacks_controller.rb
@@ -0,0 +1,54 @@
+# frozen_string_literal: true
+
+class Users::OmniauthCallbacksController < Devise::OmniauthCallbacksController
+  def github
+    handle_auth('GitHub')
+  end
+
+  def google_oauth2
+    handle_auth('Google')
+  end
+
+  def openid_connect
+    handle_auth('OpenID Connect')
+  end
+
+  def failure
+    error_type = request.env['omniauth.error.type']
+    error = request.env['omniauth.error']
+
+    # Provide user-friendly error messages
+    error_message =
+      case error_type
+      when :invalid_credentials
+        'Invalid credentials. Please check your username and password.'
+      when :timeout
+        'Connection timeout. Please try again.'
+      when :csrf_detected
+        'Security error detected. Please try again.'
+      else
+        if error&.message&.include?('Discovery')
+          'Unable to connect to authentication provider. Please contact your administrator.'
+        elsif error&.message&.include?('Issuer mismatch')
+          'Authentication provider configuration error. Please contact your administrator.'
+        else
+          "Authentication failed: #{params[:message] || error&.message || 'Unknown error'}"
+        end
+      end
+
+    redirect_to root_path, alert: error_message
+  end
+
+  private
+
+  def handle_auth(provider)
+    @user = User.from_omniauth(request.env['omniauth.auth'])
+
+    if @user.persisted?
+      flash[:notice] = I18n.t 'devise.omniauth_callbacks.success', kind: provider
+      sign_in_and_redirect @user, event: :authentication
+    else
+      redirect_to new_user_registration_url, alert: @user.errors.full_messages.join("\n")
+    end
+  end
+end
diff --git a/app/models/concerns/omniauthable.rb b/app/models/concerns/omniauthable.rb
new file mode 100644
index 00000000..b0fbb21b
--- /dev/null
+++ b/app/models/concerns/omniauthable.rb
@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+module Omniauthable
+  extend ActiveSupport::Concern
+
+  class_methods do
+    def from_omniauth(access_token)
+      data = access_token.info
+      provider = access_token.provider
+      uid = access_token.uid
+
+      # First, try to find user by provider and uid (for linked accounts)
+      user = find_by(provider: provider, uid: uid)
+
+      return user if user
+
+      # If not found, try to find by email
+      user = find_by(email: data['email'])
+
+      if user
+        # Update provider and uid for existing user (first-time linking)
+        user.update(provider: provider, uid: uid)
+        return user
+      end
+
+      # Create new user if not found
+      user = create(
+        email: data['email'],
+        password: Devise.friendly_token[0, 20],
+        provider: provider,
+        uid: uid
+      )
+
+      user
+    end
+  end
+end
diff --git a/app/models/user.rb b/app/models/user.rb
index 71269d64..d328cb20 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -2,8 +2,11 @@
 
 class User < ApplicationRecord # rubocop:disable Metrics/ClassLength
   include UserFamily
+  include Omniauthable
+
   devise :database_authenticatable, :registerable,
-         :recoverable, :rememberable, :validatable, :trackable
+         :recoverable, :rememberable, :validatable, :trackable,
+         :omniauthable, omniauth_providers: ::OMNIAUTH_PROVIDERS
 
   has_many :points, dependent: :destroy
   has_many :imports,        dependent: :destroy
diff --git a/app/views/devise/registrations/edit.html.erb b/app/views/devise/registrations/edit.html.erb
index 5536a889..52ad05db 100644
--- a/app/views/devise/registrations/edit.html.erb
+++ b/app/views/devise/registrations/edit.html.erb
@@ -64,10 +64,10 @@
         <div class="form-control mt-6">
           <%= f.submit "Update", class: 'btn btn-primary' %>
         </div>
-
-        <%= render "devise/shared/links" %>
       <% end %>
 
+      <%= render "devise/shared/links" %>
+
       <p class='mt-3'>Unhappy? <%= link_to "Cancel my account", registration_path(resource_name), data: { turbo_confirm: "Are you sure?", turbo_method: :delete }, method: :delete, class: 'btn' %></p>
       <div class="divider"></div>
       <p class='mt-3 flex flex-col gap-2'>
diff --git a/app/views/devise/registrations/new.html.erb b/app/views/devise/registrations/new.html.erb
index 4a32be9e..d367458b 100644
--- a/app/views/devise/registrations/new.html.erb
+++ b/app/views/devise/registrations/new.html.erb
@@ -74,10 +74,10 @@
           <%= f.submit (@invitation ? "Create Account & Join Family" : "Sign up"),
                 class: 'btn btn-primary' %>
         </div>
+      <% end %>
 
-        <% unless @invitation %>
-          <%= render "devise/shared/links" %>
-        <% end %>
+      <% unless @invitation %>
+        <%= render "devise/shared/links" %>
       <% end %>
     </div>
   </div>
diff --git a/app/views/devise/sessions/new.html.erb b/app/views/devise/sessions/new.html.erb
index 633337c1..a12c108c 100644
--- a/app/views/devise/sessions/new.html.erb
+++ b/app/views/devise/sessions/new.html.erb
@@ -49,10 +49,10 @@
         <div class="form-control mt-6">
           <%= f.submit (@invitation ? "Sign in & Accept Invitation" : "Log in"), class: 'btn btn-primary' %>
         </div>
+      <% end %>
 
-        <% unless @invitation %>
-          <%= render "devise/shared/links" %>
-        <% end %>
+      <% unless @invitation %>
+        <%= render "devise/shared/links" %>
       <% end %>
     </div>
   </div>
diff --git a/app/views/devise/shared/_links.html.erb b/app/views/devise/shared/_links.html.erb
index c968119a..857c7d41 100644
--- a/app/views/devise/shared/_links.html.erb
+++ b/app/views/devise/shared/_links.html.erb
@@ -1,4 +1,4 @@
-<div class='my-5'>
+<div class='mt-5'>
   <% if !signed_in? %>
     <div class='my-2'>
       <%= link_to "Log in", new_session_path(resource_name) %>
diff --git a/app/views/settings/index.html.erb b/app/views/settings/index.html.erb
index 2226c69a..d33d86b1 100644
--- a/app/views/settings/index.html.erb
+++ b/app/views/settings/index.html.erb
@@ -68,6 +68,20 @@
               </div> %>
             </div>
           </div>
+
+          <% unless DawarichSettings.self_hosted? %>
+            <div>
+              <h2 class="text-2xl font-bold mb-4 flex items-center">
+                <%= icon 'link', class: "text-primary mr-1" %> Connected Accounts
+              </h2>
+              <div class="bg-base-100 p-5 rounded-lg shadow-sm space-y-4">
+                <p class="text-sm text-base-content/70">
+                  You've connected your account using the following OAuth provider:
+                  <strong><%= current_user.provider.capitalize %></strong>
+                </p>
+              </div>
+            </div>
+          <% end %>
         </div>
         <div class="card-actions justify-end mt-6">
           <%= f.submit "Save changes", class: "btn btn-primary" %>
diff --git a/config/initializers/01_constants.rb b/config/initializers/01_constants.rb
index 1129be64..0215de24 100644
--- a/config/initializers/01_constants.rb
+++ b/config/initializers/01_constants.rb
@@ -36,3 +36,17 @@ MANAGER_URL = SELF_HOSTED ? nil : ENV.fetch('MANAGER_URL', nil)
 METRICS_USERNAME = ENV.fetch('METRICS_USERNAME', 'prometheus')
 METRICS_PASSWORD = ENV.fetch('METRICS_PASSWORD', 'prometheus')
 # /Prometheus metrics
+
+# Configure OAuth providers based on environment
+# Self-hosted: only OpenID Connect, Cloud: only GitHub and Google
+OMNIAUTH_PROVIDERS =
+  if SELF_HOSTED
+    # Self-hosted: only OpenID Connect
+    ENV['OIDC_CLIENT_ID'].present? ? %i[openid_connect] : []
+  else
+    # Cloud: only GitHub and Google
+    providers = []
+    providers << :github if ENV['GITHUB_OAUTH_CLIENT_ID'].present?
+    providers << :google_oauth2 if ENV['GOOGLE_OAUTH_CLIENT_ID'].present?
+    providers
+  end
diff --git a/config/initializers/devise.rb b/config/initializers/devise.rb
index 7b207ed3..51e15216 100644
--- a/config/initializers/devise.rb
+++ b/config/initializers/devise.rb
@@ -265,7 +265,63 @@ Devise.setup do |config|
   # ==> OmniAuth
   # Add a new OmniAuth provider. Check the wiki for more information on setting
   # up on your models and hooks.
-  # config.omniauth :github, 'APP_ID', 'APP_SECRET', scope: 'user,public_repo'
+
+  # Cloud version: only GitHub, Google (when env vars present)
+  if !SELF_HOSTED
+    if ENV['GITHUB_OAUTH_CLIENT_ID'].present? && ENV['GITHUB_OAUTH_CLIENT_SECRET'].present?
+      config.omniauth :github, ENV['GITHUB_OAUTH_CLIENT_ID'], ENV['GITHUB_OAUTH_CLIENT_SECRET'], scope: 'user:email'
+      Rails.logger.info 'OAuth: GitHub configured'
+    end
+
+    if ENV['GOOGLE_OAUTH_CLIENT_ID'].present? && ENV['GOOGLE_OAUTH_CLIENT_SECRET'].present?
+      config.omniauth :google_oauth2, ENV['GOOGLE_OAUTH_CLIENT_ID'], ENV['GOOGLE_OAUTH_CLIENT_SECRET'],
+                      scope: 'userinfo.email,userinfo.profile'
+      Rails.logger.info 'OAuth: Google configured'
+    end
+  end
+
+  # Self-hosted version: only OpenID Connect (when env vars present)
+  # Generic OpenID Connect provider (Authelia, Authentik, Keycloak, etc.)
+  # Supports both discovery mode (preferred) and manual endpoint configuration
+  if SELF_HOSTED && ENV['OIDC_CLIENT_ID'].present? && ENV['OIDC_CLIENT_SECRET'].present?
+    oidc_config = {
+      name: :openid_connect,
+      scope: %i[openid email profile],
+      response_type: :code,
+      client_options: {
+        identifier: ENV['OIDC_CLIENT_ID'],
+        secret: ENV['OIDC_CLIENT_SECRET'],
+        redirect_uri: ENV.fetch('OIDC_REDIRECT_URI', "#{ENV.fetch('APPLICATION_URL', 'http://localhost:3000')}/users/auth/openid_connect/callback")
+      }
+    }
+
+    # Use OIDC discovery if issuer is provided (recommended for Authelia, Authentik, Keycloak)
+    if ENV['OIDC_ISSUER'].present?
+      oidc_config[:issuer] = ENV['OIDC_ISSUER']
+      oidc_config[:discovery] = true
+      Rails.logger.info "OIDC: Discovery mode enabled with issuer: #{ENV['OIDC_ISSUER']}"
+    # Otherwise use manual endpoint configuration
+    elsif ENV['OIDC_HOST'].present?
+      oidc_config[:client_options].merge!(
+        {
+          host: ENV['OIDC_HOST'],
+          scheme: ENV.fetch('OIDC_SCHEME', 'https'),
+          port: ENV.fetch('OIDC_PORT', 443).to_i,
+          authorization_endpoint: ENV.fetch('OIDC_AUTHORIZATION_ENDPOINT', '/authorize'),
+          token_endpoint: ENV.fetch('OIDC_TOKEN_ENDPOINT', '/token'),
+          userinfo_endpoint: ENV.fetch('OIDC_USERINFO_ENDPOINT', '/userinfo')
+        }
+      )
+      Rails.logger.info "OIDC: Manual mode enabled with host: #{ENV['OIDC_SCHEME']}://#{ENV['OIDC_HOST']}:#{ENV.fetch(
+        'OIDC_PORT', 443
+      )}"
+    end
+
+    Rails.logger.info "OIDC: Client ID: #{ENV['OIDC_CLIENT_ID']}, Redirect URI: #{oidc_config[:client_options][:redirect_uri]}"
+    config.omniauth :openid_connect, oidc_config
+  else
+    Rails.logger.warn 'OIDC: Not configured (missing OIDC_CLIENT_ID or OIDC_CLIENT_SECRET)'
+  end
 
   # ==> Warden configuration
   # If you want to use other strategies, that are not supported by Devise, or
diff --git a/config/routes.rb b/config/routes.rb
index 38666530..16d2eacb 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -103,7 +103,8 @@ Rails.application.routes.draw do
 
   devise_for :users, controllers: {
     registrations: 'users/registrations',
-    sessions: 'users/sessions'
+    sessions: 'users/sessions',
+    omniauth_callbacks: 'users/omniauth_callbacks'
   }
 
   resources :metrics, only: [:index]
diff --git a/db/migrate/20251028130433_add_omniauth_to_users.rb b/db/migrate/20251028130433_add_omniauth_to_users.rb
new file mode 100644
index 00000000..01c61b71
--- /dev/null
+++ b/db/migrate/20251028130433_add_omniauth_to_users.rb
@@ -0,0 +1,6 @@
+class AddOmniauthToUsers < ActiveRecord::Migration[8.0]
+  def change
+    add_column :users, :provider, :string
+    add_column :users, :uid, :string
+  end
+end
diff --git a/docker/.env.example b/docker/.env.example
index 008b2af6..18efe182 100644
--- a/docker/.env.example
+++ b/docker/.env.example
@@ -139,3 +139,49 @@ APP_MEMORY_LIMIT=4G
 # SECRET_KEY_BASE=your-generated-secret-key
 # SELF_HOSTED=true
 # PROMETHEUS_EXPORTER_ENABLED=true
+
+# =============================================================================
+# Example of configuration for OpenID Connect (OIDC) authentication
+#
+# =============================================================================
+
+# Generic OpenID Connect (for Authelia, Authentik, Keycloak, etc.)
+# Option 1: Using OIDC Discovery (Recommended)
+# Set OIDC_ISSUER to your provider's issuer URL (e.g., https://auth.example.com)
+# The provider must support OpenID Connect Discovery (.well-known/openid-configuration)
+OIDC_CLIENT_ID=client_id_example
+OIDC_CLIENT_SECRET=client_secret_example
+OIDC_ISSUER=https://authentik.yourdomain.com/application/o/dawarich/
+OIDC_REDIRECT_URI=https://your-dawarich-url.com/users/auth/openid_connect/callback
+
+# Option 2: Manual Endpoint Configuration (if discovery is not supported)
+# Use this if your provider doesn't support OIDC discovery
+# OIDC_CLIENT_ID=
+# OIDC_CLIENT_SECRET=
+# OIDC_HOST=auth.example.com
+# OIDC_SCHEME=https
+# OIDC_PORT=443
+# OIDC_AUTHORIZATION_ENDPOINT=/authorize
+# OIDC_TOKEN_ENDPOINT=/token
+# OIDC_USERINFO_ENDPOINT=/userinfo
+# OIDC_REDIRECT_URI=https://yourdomain.com/users/auth/openid_connect/callback
+
+# Example configurations:
+#
+# Authelia:
+# OIDC_ISSUER=https://auth.example.com
+# OIDC_CLIENT_ID=your-client-id
+# OIDC_CLIENT_SECRET=your-client-secret
+# OIDC_REDIRECT_URI=https://dawarich.example.com/users/auth/openid_connect/callback
+#
+# Authentik:
+# OIDC_ISSUER=https://authentik.example.com/application/o/dawarich/
+# OIDC_CLIENT_ID=your-client-id
+# OIDC_CLIENT_SECRET=your-client-secret
+# OIDC_REDIRECT_URI=https://dawarich.example.com/users/auth/openid_connect/callback
+#
+# Keycloak:
+# OIDC_ISSUER=https://keycloak.example.com/realms/your-realm
+# OIDC_CLIENT_ID=dawarich
+# OIDC_CLIENT_SECRET=your-client-secret
+# OIDC_REDIRECT_URI=https://dawarich.example.com/users/auth/openid_connect/callback
diff --git a/spec/models/user_spec.rb b/spec/models/user_spec.rb
index 928df596..25770617 100644
--- a/spec/models/user_spec.rb
+++ b/spec/models/user_spec.rb
@@ -336,4 +336,97 @@ RSpec.describe User, type: :model do
       end
     end
   end
+
+  describe '.from_omniauth' do
+    let(:auth_hash) do
+      OmniAuth::AuthHash.new({
+        provider: 'github',
+        uid: '123545',
+        info: {
+          email: email,
+          name: 'Test User'
+        }
+      })
+    end
+
+    context 'when user exists with the same email' do
+      let(:email) { 'existing@example.com' }
+      let!(:existing_user) { create(:user, email: email) }
+
+      it 'returns the existing user' do
+        user = described_class.from_omniauth(auth_hash)
+        expect(user).to eq(existing_user)
+        expect(user.persisted?).to be true
+      end
+
+      it 'does not create a new user' do
+        expect do
+          described_class.from_omniauth(auth_hash)
+        end.not_to change(User, :count)
+      end
+    end
+
+    context 'when user does not exist' do
+      let(:email) { 'new@example.com' }
+
+      it 'creates a new user with the OAuth email' do
+        expect do
+          described_class.from_omniauth(auth_hash)
+        end.to change(User, :count).by(1)
+
+        user = User.last
+        expect(user.email).to eq(email)
+      end
+
+      it 'generates a random password for the new user' do
+        user = described_class.from_omniauth(auth_hash)
+        expect(user.encrypted_password).to be_present
+      end
+
+      it 'returns a persisted user' do
+        user = described_class.from_omniauth(auth_hash)
+        expect(user.persisted?).to be true
+      end
+    end
+
+    context 'when OAuth provider is Google' do
+      let(:email) { 'google@example.com' }
+      let(:auth_hash) do
+        OmniAuth::AuthHash.new({
+          provider: 'google_oauth2',
+          uid: '123545',
+          info: {
+            email: email,
+            name: 'Google User'
+          }
+        })
+      end
+
+      it 'creates a user from Google OAuth data' do
+        user = described_class.from_omniauth(auth_hash)
+        expect(user.email).to eq(email)
+        expect(user.persisted?).to be true
+      end
+    end
+
+    context 'when email is nil' do
+      let(:email) { nil }
+
+      it 'attempts to create a user but fails validation' do
+        user = described_class.from_omniauth(auth_hash)
+        expect(user.persisted?).to be false
+        expect(user.errors[:email]).to be_present
+      end
+    end
+
+    context 'when email is blank' do
+      let(:email) { '' }
+
+      it 'attempts to create a user but fails validation' do
+        user = described_class.from_omniauth(auth_hash)
+        expect(user.persisted?).to be false
+        expect(user.errors[:email]).to be_present
+      end
+    end
+  end
 end
diff --git a/spec/requests/users/omniauth_callbacks_spec.rb b/spec/requests/users/omniauth_callbacks_spec.rb
new file mode 100644
index 00000000..7fbc1b07
--- /dev/null
+++ b/spec/requests/users/omniauth_callbacks_spec.rb
@@ -0,0 +1,96 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe 'Users::OmniauthCallbacks', type: :request do
+  let(:email) { 'oauth_user@example.com' }
+
+  before do
+    Rails.application.env_config['devise.mapping'] = Devise.mappings[:user]
+  end
+
+  shared_examples 'successful OAuth authentication' do |provider, provider_name|
+    context "when user doesn't exist" do
+      it 'creates a new user and signs them in' do
+        expect do
+          Rails.application.env_config['omniauth.auth'] = OmniAuth.config.mock_auth[provider]
+          get "/users/auth/#{provider}/callback"
+        end.to change(User, :count).by(1)
+
+        expect(response).to redirect_to(root_path)
+
+        user = User.find_by(email: email)
+        expect(user).to be_present
+        expect(user.encrypted_password).to be_present
+      end
+    end
+
+    context 'when user already exists' do
+      let!(:existing_user) { create(:user, email: email) }
+
+      it 'signs in the existing user without creating a new one' do
+        expect do
+          Rails.application.env_config['omniauth.auth'] = OmniAuth.config.mock_auth[provider]
+          get "/users/auth/#{provider}/callback"
+        end.not_to change(User, :count)
+
+        expect(response).to redirect_to(root_path)
+      end
+    end
+
+    context 'when user creation fails' do
+      before do
+        allow(User).to receive(:create).and_return(
+          User.new(email: email).tap do |u|
+            u.errors.add(:email, 'is invalid')
+          end
+        )
+      end
+
+      it 'redirects to registration with error message' do
+        Rails.application.env_config['omniauth.auth'] = OmniAuth.config.mock_auth[provider]
+        get "/users/auth/#{provider}/callback"
+
+        expect(response).to redirect_to(new_user_registration_url)
+      end
+    end
+  end
+
+  # Self-hosted configuration (SELF_HOSTED=true) uses OpenID Connect
+  describe 'GET /users/auth/openid_connect/callback' do
+    before do
+      mock_openid_connect_auth(email: email)
+    end
+
+    include_examples 'successful OAuth authentication', :openid_connect, 'OpenID Connect'
+  end
+
+  describe 'OAuth flow integration with OpenID Connect' do
+    context 'with OpenID Connect (Authelia/Authentik/Keycloak)' do
+      before { mock_openid_connect_auth(email: 'oidc@example.com') }
+
+      it 'completes the full OAuth flow' do
+        expect do
+          Rails.application.env_config['omniauth.auth'] = OmniAuth.config.mock_auth[:openid_connect]
+          get '/users/auth/openid_connect/callback'
+        end.to change(User, :count).by(1)
+
+        user = User.find_by(email: 'oidc@example.com')
+        expect(user).to be_present
+        expect(user.email).to eq('oidc@example.com')
+        expect(response).to redirect_to(root_path)
+      end
+    end
+  end
+
+  describe 'CSRF protection' do
+    it 'does not raise CSRF error for OpenID Connect callback' do
+      mock_openid_connect_auth(email: email)
+
+      expect do
+        Rails.application.env_config['omniauth.auth'] = OmniAuth.config.mock_auth[:openid_connect]
+        get '/users/auth/openid_connect/callback'
+      end.not_to raise_error
+    end
+  end
+end
diff --git a/spec/support/omniauth.rb b/spec/support/omniauth.rb
new file mode 100644
index 00000000..8f809e62
--- /dev/null
+++ b/spec/support/omniauth.rb
@@ -0,0 +1,105 @@
+# frozen_string_literal: true
+
+OmniAuth.config.test_mode = true
+
+module OmniauthHelpers
+  def mock_github_auth(email: 'test@github.com')
+    OmniAuth.config.mock_auth[:github] = OmniAuth::AuthHash.new({
+      provider: 'github',
+      uid: '123545',
+      info: {
+        email: email,
+        name: 'Test User',
+        image: 'https://avatars.githubusercontent.com/u/123545'
+      },
+      credentials: {
+        token: 'mock_token',
+        expires_at: Time.now + 1.week
+      },
+      extra: {
+        raw_info: {
+          login: 'testuser',
+          avatar_url: 'https://avatars.githubusercontent.com/u/123545',
+          name: 'Test User',
+          email: email
+        }
+      }
+    })
+  end
+
+  def mock_google_auth(email: 'test@gmail.com')
+    OmniAuth.config.mock_auth[:google_oauth2] = OmniAuth::AuthHash.new({
+      provider: 'google_oauth2',
+      uid: '123545',
+      info: {
+        email: email,
+        name: 'Test User',
+        image: 'https://lh3.googleusercontent.com/a/test'
+      },
+      credentials: {
+        token: 'mock_token',
+        refresh_token: 'mock_refresh_token',
+        expires_at: Time.now + 1.hour
+      },
+      extra: {
+        raw_info: {
+          email: email,
+          email_verified: true,
+          name: 'Test User',
+          given_name: 'Test',
+          family_name: 'User',
+          picture: 'https://lh3.googleusercontent.com/a/test'
+        }
+      }
+    })
+  end
+
+  def mock_openid_connect_auth(email: 'test@oidc.com', provider_name: 'Authelia')
+    OmniAuth.config.mock_auth[:openid_connect] = OmniAuth::AuthHash.new({
+      provider: 'openid_connect',
+      uid: '123545',
+      info: {
+        email: email,
+        name: 'Test User',
+        image: 'https://example.com/avatar.jpg'
+      },
+      credentials: {
+        token: 'mock_token',
+        refresh_token: 'mock_refresh_token',
+        expires_at: Time.now + 1.hour,
+        id_token: 'mock_id_token'
+      },
+      extra: {
+        raw_info: {
+          sub: '123545',
+          email: email,
+          email_verified: true,
+          name: 'Test User',
+          preferred_username: 'testuser',
+          given_name: 'Test',
+          family_name: 'User',
+          picture: 'https://example.com/avatar.jpg'
+        }
+      }
+    })
+  end
+
+  def mock_oauth_failure(provider)
+    OmniAuth.config.mock_auth[provider] = :invalid_credentials
+  end
+end
+
+RSpec.configure do |config|
+  config.include OmniauthHelpers, type: :request
+  config.include OmniauthHelpers, type: :system
+
+  config.before do
+    OmniAuth.config.test_mode = true
+  end
+
+  config.after do
+    OmniAuth.config.mock_auth[:github] = nil
+    OmniAuth.config.mock_auth[:google_oauth2] = nil
+    OmniAuth.config.mock_auth[:openid_connect] = nil
+  end
+end