diff --git a/Command/GraphQLConfigureCommand.php b/Command/GraphQLConfigureCommand.php
index 6a2dbfb..5994125 100644
--- a/Command/GraphQLConfigureCommand.php
+++ b/Command/GraphQLConfigureCommand.php
@@ -13,7 +13,7 @@
 
 class GraphQLConfigureCommand extends Command
 {
-    const PROJECT_NAMESPACE = 'App';
+    public const PROJECT_NAMESPACE = 'App';
 
     /** @var Container */
     protected $container;
@@ -80,7 +80,7 @@ protected function execute(InputInterface $input, OutputInterface $output)
             }
 
             $originalConfigData = file_get_contents($configFile);
-            if (strpos($originalConfigData, 'graphql') === false) {
+            if (!str_contains($originalConfigData, 'graphql')) {
                 $projectNameSpace = self::PROJECT_NAMESPACE;
                 $configData       = <<<CONFIG
 graphql:
@@ -119,7 +119,7 @@ protected function getMainRouteConfig()
         $routerResources = $this->container->get('router')->getRouteCollection()->getResources();
         foreach ($routerResources as $resource) {
             /** @var FileResource|DirectoryResource $resource */
-            if (method_exists($resource, 'getResource') && substr($resource->getResource(), -11) == 'routes.yaml') {
+            if (method_exists($resource, 'getResource') && str_ends_with($resource->getResource(), 'routes.yaml')) {
                 return $resource->getResource();
             }
         }
@@ -136,7 +136,7 @@ protected function graphQLRouteExists()
         $routerResources = $this->container->get('router')->getRouteCollection()->getResources();
         foreach ($routerResources as $resource) {
             /** @var FileResource|DirectoryResource $resource */
-            if (method_exists($resource, 'getResource') && strpos($resource->getResource(), 'GraphQLController.php') !== false) {
+            if (method_exists($resource, 'getResource') && str_contains($resource->getResource(), 'GraphQLController.php')) {
                 return true;
             }
         }
diff --git a/Config/Rule/TypeValidationRule.php b/Config/Rule/TypeValidationRule.php
index c4597e7..a457ecc 100644
--- a/Config/Rule/TypeValidationRule.php
+++ b/Config/Rule/TypeValidationRule.php
@@ -22,7 +22,7 @@ public function validate($data, $ruleInfo)
 
         if (($ruleInfo == TypeService::TYPE_CALLABLE) && (
                 is_callable($data) ||
-                (is_array($data) && count($data) == 2 && substr($data[0], 0, 1) == '@'))
+                (is_array($data) && count($data) == 2 && str_starts_with((string) $data[0], '@')))
         ) {
             return true;
         }
diff --git a/Controller/GraphQLController.php b/Controller/GraphQLController.php
index 1287137..141880a 100644
--- a/Controller/GraphQLController.php
+++ b/Controller/GraphQLController.php
@@ -20,12 +20,10 @@
 class GraphQLController extends AbstractController
 {
     protected $container;
-    protected $params;
 
-    public function __construct(ContainerInterface $container, ParameterBagInterface $params)
+    public function __construct(ContainerInterface $container, protected ParameterBagInterface $params)
     {
         $this->container = $container;
-        $this->params = $params;
     }
 
     /**
@@ -35,11 +33,11 @@ public function __construct(ContainerInterface $container, ParameterBagInterface
      *
      * @return JsonResponse
      */
-    public function defaultAction()
+    public function defaultAction(): JsonResponse
     {
         try {
             $this->initializeSchemaService();
-        } catch (UnableToInitializeSchemaServiceException $e) {
+        } catch (UnableToInitializeSchemaServiceException) {
             return new JsonResponse(
                 [['message' => 'Schema class ' . $this->getSchemaClass() . ' does not exist']],
                 200,
@@ -47,15 +45,13 @@ public function defaultAction()
             );
         }
 
-        if ($this->container->get('request_stack')->getCurrentRequest()->getMethod() == 'OPTIONS') {
+        if ($this->container->get('request_stack')->getCurrentRequest()->getMethod() === 'OPTIONS') {
             return $this->createEmptyResponse();
         }
 
-        list($queries, $isMultiQueryRequest) = $this->getPayload();
+        [$queries, $isMultiQueryRequest] = $this->getPayload();
 
-        $queryResponses = array_map(function ($queryData) {
-            return $this->executeQuery($queryData['query'], $queryData['variables']);
-        }, $queries);
+        $queryResponses = array_map(fn($queryData) => $this->executeQuery($queryData['query'], $queryData['variables']), $queries);
 
         $response = new JsonResponse($isMultiQueryRequest ? $queryResponses : $queryResponses[0], 200, $this->getParam('graphql.response.headers'));
 
@@ -66,12 +62,12 @@ public function defaultAction()
         return $response;
     }
 
-    protected function createEmptyResponse()
+    protected function createEmptyResponse(): JsonResponse
     {
         return new JsonResponse([], 200, $this->getResponseHeaders());
     }
 
-    protected function executeQuery($query, $variables)
+    protected function executeQuery($query, $variables): array
     {
         /** @var Processor $processor */
         $processor = $this->container->get('graphql.processor');
@@ -85,7 +81,7 @@ protected function executeQuery($query, $variables)
      *
      * @throws \Exception
      */
-    protected function getPayload()
+    protected function getPayload(): array
     {
         $request = $this->container->get('request_stack')->getCurrentRequest();
         $query = $request->get('query', null);
@@ -103,7 +99,7 @@ protected function getPayload()
                     'variables' => [],
                 ];
             } else {
-                $params = json_decode($content, true);
+                $params = json_decode((string) $content, true);
 
                 if ($params) {
                     // check for a list of queries
@@ -114,7 +110,7 @@ protected function getPayload()
                     }
 
                     foreach ($params as $queryParams) {
-                        $query = isset($queryParams['query']) ? $queryParams['query'] : $query;
+                        $query = $queryParams['query'] ?? $query;
 
                         if (isset($queryParams['variables'])) {
                             if (is_string($queryParams['variables'])) {
@@ -198,7 +194,7 @@ protected function getSchemaService()
     {
         $serviceName = $this->getParam('graphql.schema_service');
 
-        if (substr($serviceName ?: '', 0, 1) === '@') {
+        if (str_starts_with($serviceName ?: '', '@')) {
             return substr($serviceName, 1, strlen($serviceName) - 1);
         }
 
diff --git a/DependencyInjection/Compiler/GraphQlCompilerPass.php b/DependencyInjection/Compiler/GraphQlCompilerPass.php
index 3ac75a4..025f9ea 100644
--- a/DependencyInjection/Compiler/GraphQlCompilerPass.php
+++ b/DependencyInjection/Compiler/GraphQlCompilerPass.php
@@ -25,7 +25,7 @@ class GraphQlCompilerPass implements CompilerPassInterface
     public function process(ContainerBuilder $container)
     {
         if ($loggerAlias = $container->getParameter('graphql.logger')) {
-            if (strpos($loggerAlias, '@') === 0) {
+            if (str_starts_with($loggerAlias, '@')) {
                 $loggerAlias = substr($loggerAlias, 1);
             }
 
diff --git a/DependencyInjection/Configuration.php b/DependencyInjection/Configuration.php
index 57c6917..d71069f 100644
--- a/DependencyInjection/Configuration.php
+++ b/DependencyInjection/Configuration.php
@@ -16,7 +16,7 @@ class Configuration implements ConfigurationInterface
     /**
      * {@inheritdoc}
      */
-    public function getConfigTreeBuilder()
+    public function getConfigTreeBuilder(): TreeBuilder
     {
         $treeBuilder = new TreeBuilder('graphql');
         $rootNode    = $treeBuilder->getRootNode();
diff --git a/DependencyInjection/GraphQLExtension.php b/DependencyInjection/GraphQLExtension.php
index a635fa6..ab43f6b 100644
--- a/DependencyInjection/GraphQLExtension.php
+++ b/DependencyInjection/GraphQLExtension.php
@@ -25,7 +25,7 @@ public function load(array $configs, ContainerBuilder $container)
         $this->config  = $this->processConfiguration($configuration, $configs);
 
         $preparedHeaders = [];
-        $headers         = $this->config['response']['headers'] ? $this->config['response']['headers'] : $this->getDefaultHeaders();
+        $headers         = $this->config['response']['headers'] ?: $this->getDefaultHeaders();
         foreach ($headers as $header) {
             $preparedHeaders[$header['name']] = $header['value'];
         }
diff --git a/Dockerfile b/Dockerfile
new file mode 100644
index 0000000..0b42819
--- /dev/null
+++ b/Dockerfile
@@ -0,0 +1,11 @@
+FROM php:8.3
+COPY --from=composer:latest /usr/bin/composer /usr/local/bin/composer
+RUN apt update
+RUN apt install git -y
+RUN apt-get install -y \
+        libzip-dev \
+        zip \
+  && docker-php-ext-install zip
+RUN pecl install xdebug && docker-php-ext-enable xdebug
+WORKDIR /var/www/html
+ENTRYPOINT ["tail", "-f", "/dev/null"]
diff --git a/Event/ResolveEvent.php b/Event/ResolveEvent.php
index ded147f..1028586 100644
--- a/Event/ResolveEvent.php
+++ b/Event/ResolveEvent.php
@@ -8,16 +8,6 @@
 
 class ResolveEvent extends GenericEvent
 {
-    /**
-     * @var Field */
-    private $field;
-
-    /** @var array */
-    private $astFields;
-    
-    /** @var mixed|null */
-    private $resolvedValue;
-
     /**
      * Constructor.
      *
@@ -25,12 +15,9 @@ class ResolveEvent extends GenericEvent
      * @param array $astFields
      * @param mixed|null $resolvedValue
      */
-    public function __construct(FieldInterface $field, array $astFields, $resolvedValue = null)
+    public function __construct(private readonly FieldInterface $field, private readonly array $astFields, private $resolvedValue = null)
     {
-        $this->field = $field;
-        $this->astFields = $astFields;
-        $this->resolvedValue = $resolvedValue;
-        parent::__construct('ResolveEvent', [$field, $astFields, $resolvedValue]);
+        parent::__construct('ResolveEvent', [$this->field, $this->astFields, $this->resolvedValue]);
     }
 
     /**
diff --git a/Execution/Processor.php b/Execution/Processor.php
index a21a0ab..078922f 100644
--- a/Execution/Processor.php
+++ b/Execution/Processor.php
@@ -30,19 +30,15 @@ class Processor extends BaseProcessor
     /** @var  SecurityManagerInterface */
     private $securityManager;
 
-    /** @var EventDispatcherInterface */
-    private $eventDispatcher;
-
     /**
      * Constructor.
      *
      * @param ExecutionContextInterface $executionContext
      * @param EventDispatcherInterface $eventDispatcher
      */
-    public function __construct(ExecutionContextInterface $executionContext, EventDispatcherInterface $eventDispatcher)
+    public function __construct(ExecutionContextInterface $executionContext, private readonly EventDispatcherInterface $eventDispatcher)
     {
         $this->executionContext = $executionContext;
-        $this->eventDispatcher = $eventDispatcher;
 
         parent::__construct($executionContext->getSchema());
     }
@@ -105,7 +101,7 @@ protected function doResolve(FieldInterface $field, AstFieldInterface $ast, $par
 
         if (($field instanceof AbstractField) && ($resolveFunc = $field->getConfig()->getResolveFunction())) {
             if ($this->isServiceReference($resolveFunc)) {
-                $service = substr($resolveFunc[0], 1);
+                $service = substr((string) $resolveFunc[0], 1);
                 $method  = $resolveFunc[1];
                 if (!$this->executionContext->getContainer()->has($service)) {
                     throw new ResolveException(sprintf('Resolve service "%s" not found for field "%s"', $service, $field->getName()));
@@ -153,7 +149,7 @@ private function assertClientHasFieldAccess(ResolveInfo $resolveInfo)
 
     private function isServiceReference($resolveFunc)
     {
-        return is_array($resolveFunc) && count($resolveFunc) == 2 && strpos($resolveFunc[0], '@') === 0;
+        return is_array($resolveFunc) && count($resolveFunc) == 2 && str_starts_with((string) $resolveFunc[0], '@');
     }
 
     public function setLogger($logger = null)
diff --git a/Security/Manager/DefaultSecurityManager.php b/Security/Manager/DefaultSecurityManager.php
index 96d2ef0..37ad7dd 100644
--- a/Security/Manager/DefaultSecurityManager.php
+++ b/Security/Manager/DefaultSecurityManager.php
@@ -22,14 +22,10 @@ class DefaultSecurityManager implements SecurityManagerInterface
     /** @var bool */
     private $rootOperationSecurityEnabled = false;
 
-    /** @var  AuthorizationCheckerInterface */
-    private $authorizationChecker;
-
-    public function __construct(AuthorizationCheckerInterface $authorizationChecker, array $guardConfig = [])
+    public function __construct(private readonly AuthorizationCheckerInterface $authorizationChecker, array $guardConfig = [])
     {
-        $this->authorizationChecker         = $authorizationChecker;
-        $this->fieldSecurityEnabled         = isset($guardConfig['field']) ? $guardConfig['field'] : false;
-        $this->rootOperationSecurityEnabled = isset($guardConfig['operation']) ? $guardConfig['operation'] : false;
+        $this->fieldSecurityEnabled         = $guardConfig['field'] ?? false;
+        $this->rootOperationSecurityEnabled = $guardConfig['operation'] ?? false;
     }
 
     /**
diff --git a/Security/Manager/SecurityManagerInterface.php b/Security/Manager/SecurityManagerInterface.php
index a1e7928..ab9aa61 100644
--- a/Security/Manager/SecurityManagerInterface.php
+++ b/Security/Manager/SecurityManagerInterface.php
@@ -13,8 +13,8 @@
 interface SecurityManagerInterface
 {
 
-    const RESOLVE_ROOT_OPERATION_ATTRIBUTE = 'RESOLVE_ROOT_OPERATION';
-    const RESOLVE_FIELD_ATTRIBUTE          = 'RESOLVE_FIELD';
+    public const RESOLVE_ROOT_OPERATION_ATTRIBUTE = 'RESOLVE_ROOT_OPERATION';
+    public const RESOLVE_FIELD_ATTRIBUTE          = 'RESOLVE_FIELD';
 
     /**
      * @param $attribute string
diff --git a/Security/Voter/AbstractListVoter.php b/Security/Voter/AbstractListVoter.php
index 611801f..475d2d3 100644
--- a/Security/Voter/AbstractListVoter.php
+++ b/Security/Voter/AbstractListVoter.php
@@ -21,7 +21,7 @@ abstract class AbstractListVoter extends Voter
     /** @var bool */
     private $enabled = false;
 
-    protected function supports($attribute, $subject)
+    protected function supports($attribute, $subject): bool
     {
         return $this->enabled && $attribute == SecurityManagerInterface::RESOLVE_ROOT_OPERATION_ATTRIBUTE;
     }
diff --git a/Security/Voter/BlacklistVoter.php b/Security/Voter/BlacklistVoter.php
index 379719d..2e04f80 100644
--- a/Security/Voter/BlacklistVoter.php
+++ b/Security/Voter/BlacklistVoter.php
@@ -23,7 +23,7 @@ class BlacklistVoter extends AbstractListVoter
      *
      * @return bool
      */
-    protected function voteOnAttribute($attribute, $subject, TokenInterface $token)
+    protected function voteOnAttribute($attribute, $subject, TokenInterface $token): bool
     {
         /** @var $subject Query */
         return $this->isLoggedInUser($token) || !$this->inList($subject->getName());
diff --git a/Tests/DependencyInjection/GraphQLExtensionTest.php b/Tests/DependencyInjection/GraphQLExtensionTest.php
index debee25..43e305e 100644
--- a/Tests/DependencyInjection/GraphQLExtensionTest.php
+++ b/Tests/DependencyInjection/GraphQLExtensionTest.php
@@ -66,7 +66,7 @@ public function testDefaultCanBeOverridden()
         );
     }
 
-    private function loadContainerFromFile($file, $type, array $services = array(), $skipEnvVars = false)
+    private function loadContainerFromFile($file, $type, array $services = [], $skipEnvVars = false)
     {
         $container = new ContainerBuilder();
         if ($skipEnvVars && !method_exists($container, 'resolveEnvPlaceholders')) {
@@ -80,25 +80,16 @@ private function loadContainerFromFile($file, $type, array $services = array(),
         $container->registerExtension(new GraphQLExtension());
         $locator = new FileLocator(__DIR__ . '/Fixtures/config/' . $type);
 
-        switch ($type) {
-            case 'xml':
-                $loader = new XmlFileLoader($container, $locator);
-                break;
-            case 'yml':
-                $loader = new YamlFileLoader($container, $locator);
-                break;
-            case 'php':
-                $loader = new PhpFileLoader($container, $locator);
-                break;
-            default:
-                throw new \InvalidArgumentException('Invalid file type');
-        }
+        $loader = match ($type) {
+            'xml' => new XmlFileLoader($container, $locator),
+            'yml' => new YamlFileLoader($container, $locator),
+            'php' => new PhpFileLoader($container, $locator),
+            default => throw new \InvalidArgumentException('Invalid file type'),
+        };
 
         $loader->load($file . '.' . $type);
-        $container->getCompilerPassConfig()->setOptimizationPasses(array(
-            new ResolveChildDefinitionsPass(),
-        ));
-        $container->getCompilerPassConfig()->setRemovingPasses(array());
+        $container->getCompilerPassConfig()->setOptimizationPasses([new ResolveChildDefinitionsPass()]);
+        $container->getCompilerPassConfig()->setRemovingPasses([]);
         $container->compile();
         return $container;
     }
diff --git a/composer.json b/composer.json
index 0834bd0..c16a83f 100644
--- a/composer.json
+++ b/composer.json
@@ -17,15 +17,22 @@
       "Youshido\\GraphQLBundle\\": ""
     }
   },
+  "repositories": [
+    {
+      "type": "vcs",
+      "url": "https://github.com/msklenica/GraphQL-php.git"
+    }
+  ],
   "require": {
-    "99designs/graphql": "~1",
-    "symfony/security-core": "~4.4 || ~5.4",
-    "symfony/framework-bundle": "~4.4 || ~5.4",
-    "php": ">=5.6"
+    "php": "^8.3",
+    "99designs/graphql": "v1.0.2",
+    "symfony/security-core": "~6.4",
+    "symfony/framework-bundle": "~6.4",
+    "symfony/console": "~6.4"
   },
   "require-dev": {
     "phpunit/phpunit": "~9.6",
-    "composer/composer": "~1.2",
-    "symfony/yaml": "~4.4 || ~5.4"
+    "rector/rector": "*",
+    "symfony/yaml": "~6.4"
   }
 }
diff --git a/docker-compose.yml b/docker-compose.yml
new file mode 100644
index 0000000..bf353c9
--- /dev/null
+++ b/docker-compose.yml
@@ -0,0 +1,7 @@
+services:
+  app:
+    hostname: app
+    container_name: app
+    build: .
+    volumes:
+      - .:/var/www/html:rw
diff --git a/rector.php b/rector.php
new file mode 100644
index 0000000..08e1bb3
--- /dev/null
+++ b/rector.php
@@ -0,0 +1,32 @@
+<?php
+declare(strict_types=1);
+
+use Rector\Config\RectorConfig;
+use Rector\PHPUnit\Set\PHPUnitSetList;
+
+return RectorConfig::configure()
+    ->withPaths([
+        __DIR__ . '/Command',
+        __DIR__ . '/Config',
+        __DIR__ . '/Controller',
+        __DIR__ . '/DependencyInjection',
+        __DIR__ . '/Event',
+        __DIR__ . '/Exception',
+        __DIR__ . '/Execution',
+        __DIR__ . '/Field',
+        __DIR__ . '/Resources',
+        __DIR__ . '/Security',
+        __DIR__ . '/Tests',
+    ])
+    ->withPhpSets(php83: true)
+    ->withSets([
+        PHPUnitSetList::PHPUNIT_50,
+        PHPUnitSetList::PHPUNIT_60,
+        PHPUnitSetList::PHPUNIT_70,
+        PHPUnitSetList::PHPUNIT_80,
+        PHPUnitSetList::PHPUNIT_90,
+    ])    ->withSkip([
+        \Rector\Php83\Rector\ClassMethod\AddOverrideAttributeToOverriddenMethodsRector::class,
+        \Rector\Php83\Rector\ClassConst\AddTypeToConstRector::class,
+        \Rector\Php82\Rector\Class_\ReadOnlyClassRector::class,
+    ]);