diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..f0194b3
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,49 @@
+name: CI
+
+on:
+  push:
+    branches: [ main, develop ]
+  pull_request:
+    branches: [ main, develop ]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        php-versions: ['8.1', '8.3']
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php-versions }}
+
+      - name: Print PHP version
+        run: php -v
+
+      - name: Cache Composer packages
+        id: composer-cache
+        uses: actions/cache@v4
+        with:
+          path: vendor
+          key: ${{ runner.os }}-php-${{ hashFiles('**/composer.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-php-
+
+      - name: Validate composer.json
+        run: composer validate
+
+      - name: Install dependencies
+        run: composer install --optimize-autoloader --no-progress --no-interaction --prefer-dist
+
+      - name: Run tests
+        run: vendor/bin/phpunit --testdox
+
+      - name: Run PHPStan
+        run: vendor/bin/phpstan analyse --level 8 --no-interaction --no-progress src
+
+      - name: Run PHPCS
+        run: vendor/bin/phpcs src tests --standard=psr2 -s
diff --git a/composer.json b/composer.json
index 0b0c0e8..7922282 100644
--- a/composer.json
+++ b/composer.json
@@ -33,6 +33,7 @@
     "require-dev": {
         "phpunit/phpunit": "^10.5",
         "squizlabs/php_codesniffer": "^3.8",
-        "mockery/mockery": "^1.6"
+        "mockery/mockery": "^1.6",
+        "phpstan/phpstan": "^1.10"
     }
 }
diff --git a/src/Provider/Galette.php b/src/Provider/Galette.php
index fffcdd4..c0ef197 100644
--- a/src/Provider/Galette.php
+++ b/src/Provider/Galette.php
@@ -29,10 +29,14 @@ class Galette extends AbstractProvider
     protected string $pluginDirectory = 'plugin-oauth2';
 
     /**
-     * @var array
+     * @var string[]
      */
     protected array $scope;
 
+    /**
+     * @param array<string, mixed> $options
+     * @param array<string, mixed> $collaborators
+     */
     public function __construct(array $options = [], array $collaborators = [])
     {
         if (!isset($options['instance'])) {
@@ -62,38 +66,56 @@ public function getBaseURL(): string
         );
     }
 
-    public function getBaseAuthorizationUrl()
+    public function getBaseAuthorizationUrl(): string
     {
         return $this->getBaseURL() . '/authorize';
     }
 
-    public function getBaseAccessTokenUrl(array $params)
+    /**
+     * @param array<string, mixed> $params
+     * @return string
+     */
+    public function getBaseAccessTokenUrl(array $params): string
     {
         return $this->getBaseURL() . '/access_token';
     }
 
-    public function getResourceOwnerDetailsUrl(AccessToken $token)
+    public function getResourceOwnerDetailsUrl(AccessToken $token): string
     {
         return $this->getBaseURL() . '/user';
     }
 
-    protected function getDefaultScopes()
+    /**
+     * @return string[]
+     */
+    protected function getDefaultScopes(): array
     {
         return [];
     }
 
+    /**
+     * @param ResponseInterface $response
+     * @param string|array<string, string> $data
+     * @return void
+     * @throws IdentityProviderException
+     */
     protected function checkResponse(ResponseInterface $response, $data)
     {
         $statusCode = $response->getStatusCode();
         if ($statusCode > 400) {
             throw new IdentityProviderException(
-                $data['message'] ?: $response->getReasonPhrase(),
+                (is_array($data) && $data['message']) ? $data['message'] : $response->getReasonPhrase(),
                 $statusCode,
                 $response
             );
         }
     }
 
+    /**
+     * @param array<string, mixed> $response
+     * @param AccessToken $token
+     * @return GaletteResourceOwner
+     */
     protected function createResourceOwner(array $response, AccessToken $token)
     {
         return new GaletteResourceOwner($response);
diff --git a/src/Provider/GaletteResourceOwner.php b/src/Provider/GaletteResourceOwner.php
index dcbef0c..35703b9 100644
--- a/src/Provider/GaletteResourceOwner.php
+++ b/src/Provider/GaletteResourceOwner.php
@@ -7,13 +7,16 @@
 
 class GaletteResourceOwner implements ResourceOwnerInterface
 {
-	use ArrayAccessorTrait;
+    use ArrayAccessorTrait;
 
     /**
      * @var array<string, mixed>
      */
     protected array $response;
 
+    /**
+     * @param array<string, mixed> $response
+     */
     public function __construct(array $response = [])
     {
         $this->response = $response;
@@ -73,10 +76,10 @@ public function getStatus(): ?int
     /**
      * Return all owner details available as an array.
      *
-     * @return array
+     * @return array<string, mixed>
      */
     public function toArray(): array
     {
         return $this->response;
     }
-}
\ No newline at end of file
+}
diff --git a/tests/src/Provider/GaletteTest.php b/tests/src/Provider/GaletteTest.php
index 39e5c15..d22d78e 100644
--- a/tests/src/Provider/GaletteTest.php
+++ b/tests/src/Provider/GaletteTest.php
@@ -60,7 +60,6 @@ public function testGetAuthorizationUrl()
     public function testGetAccessToken()
     {
         $response = m::mock('Psr\Http\Message\ResponseInterface');
-        //$response->shouldReceive('getBody')->andReturn('{"access_token": "mock_access_token", "token_type": "bearer", "account_id": "12345", "uid": "deprecated_id"}');
         $response
             ->shouldReceive('getBody')
             ->andReturn(
@@ -117,7 +116,8 @@ public function testUserData()
             ->andReturn(
                 new Stream(
                     fopen(
-                        'data://text/plain,{"id": '.$userId.', "username": "'.$username.'", "email": "'.$email.'", "language": "'.$lang.'", "status": '.$status.'}',
+                        'data://text/plain,{"id": '.$userId.', "username": "'.$username.'", "email": "'.
+                        $email.'", "language": "'.$lang.'", "status": '.$status.'}',
                         'r'
                     )
                 )
@@ -156,7 +156,7 @@ public function testUserData()
     public function testUserDataFails()
     {
         $this->expectException(\League\OAuth2\Client\Provider\Exception\IdentityProviderException::class);
-        $status = rand(400,600);
+        $status = rand(400, 600);
 
         $postResponse = m::mock('Psr\Http\Message\ResponseInterface');
         $postResponse