diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
new file mode 100644
index 0000000..4b37c43
--- /dev/null
+++ b/.github/workflows/tests.yml
@@ -0,0 +1,50 @@
+name: Tests
+
+on:
+  push:
+    branches: [2.0, 3.0, main, master]
+  pull_request:
+    branches: [2.0, 3.0, main, master]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    strategy:
+      fail-fast: true
+      matrix:
+        php: [8.1, 8.2, 8.3]
+        laravel: [10.*, 11.*, 12.*]
+        include:
+          - laravel: 10.*
+            testbench: 8.*
+          - laravel: 11.*
+            testbench: 9.*
+          - laravel: 12.*
+            testbench: 10.*
+        exclude:
+          - php: 8.1
+            laravel: 11.*
+          - php: 8.1
+            laravel: 12.*
+
+    name: PHP ${{ matrix.php }} - Laravel ${{ matrix.laravel }}
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php }}
+          extensions: dom, curl, libxml, mbstring, zip, pcntl, pdo, sqlite, pdo_sqlite
+          coverage: none
+
+      - name: Install dependencies
+        run: |
+          composer require "laravel/framework:${{ matrix.laravel }}" "orchestra/testbench:${{ matrix.testbench }}" --no-interaction --no-update
+          composer update --prefer-dist --no-interaction
+
+      - name: Execute tests
+        run: vendor/bin/phpunit
diff --git a/.scrutinizer.yml b/.scrutinizer.yml
index 9a78174..55c943e 100644
--- a/.scrutinizer.yml
+++ b/.scrutinizer.yml
@@ -18,11 +18,14 @@ checks:
     fix_doc_comments: true
 
 build:
+  environment:
+    php:
+      version: 8.2
   tests:
     override:
       - php-scrutinizer-run
       -
-        command: 'vendor/bin/phpunit --coverage-clover=some-file'
+        command: 'vendor/bin/phpunit --coverage-clover=coverage.xml'
         coverage:
-          file: 'some-file'
+          file: 'coverage.xml'
           format: 'clover'
diff --git a/.styleci.yml b/.styleci.yml
index 473c31a..9b6f8d9 100644
--- a/.styleci.yml
+++ b/.styleci.yml
@@ -1,7 +1,9 @@
 preset: laravel
 
+risky: true
+
 finder:
   exclude:
-    - "tests"
+    - tests
   name:
     - "*.php"
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index b62eb3c..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,59 +0,0 @@
-language: php
-
-env:
-  global:
-    - setup=stable
-
-matrix:
-  include:
-    - php: 7.0
-      env:
-        - testbench=3.4.x
-        - phpunit=5.7.x
-    - php: 7.0
-      env:
-        - testbench=3.5.x
-        - phpunit=6.0.x
-    - php: 7.1
-      env:
-        - testbench=3.5.x
-        - phpunit=6.0.x
-    - php: 7.1
-      env:
-        - testbench=3.6.x
-        - phpunit=7.0.x
-    - php: 7.1
-      env:
-        - testbench=3.6.x
-        - phpunit=7.0.x
-    - php: 7.1
-      env:
-        - testbench=3.7.x
-        - phpunit=7.0.x
-    - php: 7.2
-      env:
-        - testbench=3.5.x
-        - phpunit=6.0.x
-    - php: 7.2
-      env:
-        - testbench=3.6.x
-        - phpunit=7.0.x
-    - php: 7.2
-      env:
-        - testbench=3.6.x
-        - phpunit=7.0.x
-    - php: 7.2
-      env:
-        - testbench=3.7.x
-        - phpunit=7.0.x
-
-sudo: false
-
-install:
-  - composer require orchestra/testbench:${testbench} --dev --no-update
-  - composer require phpunit/phpunit:${phpunit} --dev --no-update
-  - if [[ $setup = 'stable' ]]; then travis_retry composer update --prefer-dist --no-interaction --prefer-stable; fi
-  - if [[ $setup = 'lowest' ]]; then travis_retry composer update --prefer-dist --no-interaction --prefer-lowest --prefer-stable; fi
-
-script:
-  - vendor/bin/phpunit
diff --git a/README.md b/README.md
index 2f5277f..6ed4112 100644
--- a/README.md
+++ b/README.md
@@ -1,20 +1,20 @@
 # Laravel Json Exception Handler
 
-[![StyleCI](https://styleci.io/repos/101529653/shield?style=plastic&branch=2.0)](https://styleci.io/repos/101529653?style=plastic&branch=2.0)
-[![Scrutinizer Code Quality](https://scrutinizer-ci.com/g/sfelix-martins/json-exception-handler/badges/quality-score.png?b=2.0)](https://scrutinizer-ci.com/g/sfelix-martins/json-exception-handler/?branch=2.0)
-[![Build Status](https://travis-ci.org/sfelix-martins/json-exception-handler.svg?branch=2.0)](https://travis-ci.org/sfelix-martins/json-exception-handler)
+[![StyleCI](https://styleci.io/repos/101529653/shield?style=plastic&branch=3.0)](https://styleci.io/repos/101529653?style=plastic&branch=3.0)
+[![Scrutinizer Code Quality](https://scrutinizer-ci.com/g/sfelix-martins/json-exception-handler/badges/quality-score.png?b=3.0)](https://scrutinizer-ci.com/g/sfelix-martins/json-exception-handler/?branch=3.0)
+[![Tests](https://github.com/sfelix-martins/json-exception-handler/actions/workflows/tests.yml/badge.svg)](https://github.com/sfelix-martins/json-exception-handler/actions/workflows/tests.yml)
 
 Adds methods to your `App\Exceptions\Handler` to treat json responses.
 It is most useful if you are building APIs!
 
 ## Requirements
 
-* Laravel Framework >= 5.4
-* php >= 7.0
+* PHP >= 8.1
+* Laravel Framework 10.x, 11.x, or 12.x
 
 ## JsonAPI
 
-Using [JsonAPI](http://jsonapi.org) standard to  responses!
+Using [JsonAPI](http://jsonapi.org) standard to responses!
 
 ## Features
 
@@ -76,26 +76,18 @@ To `Illuminate\Validation\ValidationException`:
 
 ## Installing and configuring
 
-Install the package 
+Install the package
 
 ```console
 $ composer require sfelix-martins/json-exception-handler
 ```
 
-If you are not using **Laravel 5.5** version add the `JsonHandlerServiceProvider` to your `config/app.php` providers array:
-
-```php
-    'providers' => [
-        ...
-        SMartins\Exceptions\JsonHandlerServiceProvider::class,
-    ],
-```
+The package uses Laravel's auto-discovery feature, so the service provider will be automatically registered.
 
 Publish the config to set your own exception codes
 
 ```sh
-
-$ php artisan vendor:publish --provider="SMartins\JsonHandler\JsonHandlerServiceProvider"
+$ php artisan vendor:publish --provider="SMartins\Exceptions\JsonHandlerServiceProvider"
 ```
 
 Set your exception codes on `config/json-exception-handler.php` on codes array.
@@ -115,12 +107,12 @@ In `resources/lang/vendor/exception/lang/$locale` in `exceptions` file you can s
 
 ## Using
 
-Use the trait on your `App\Exception\Handler` and add method `jsonResponse()` 
-passing the `$exception` if `$request` expects a json response on `render()`method
+Use the trait on your `App\Exception\Handler` and add method `jsonResponse()`
+passing the `$exception` if `$request` expects a json response on `render()` method
 
 ```php
-
 use SMartins\Exceptions\JsonHandler;
+use Throwable;
 
 class Handler extends ExceptionHandler
 {
@@ -128,15 +120,15 @@ class Handler extends ExceptionHandler
 
     // ...
 
-    public function render($request, Exception $exception)
-    {   
+    public function render($request, Throwable $e)
+    {
         if ($request->expectsJson()) {
-            return $this->jsonResponse($exception);
+            return $this->jsonResponse($e);
         }
 
-        return parent::render($request, $exception);
+        return parent::render($request, $e);
     }
-    
+
     // ...
 ```
 
@@ -173,7 +165,7 @@ class UserController extends Controller
     {
         // If not found the default response is called
         $user = User::findOrFail($id);
-        
+
         // Gate define on AuthServiceProvider
         // Generate an AuthorizationException if fail
         $this->authorize('users.view', $user->id);
@@ -183,54 +175,37 @@ class UserController extends Controller
 
 ## Extending
 
-You can too create your own handler to any Exception. E.g.:
+You can create your own handler for any Exception. E.g.:
 
-- Create a Handler class that extends of `AbstractHandler`:
+- Create a Handler class that extends `AbstractHandler`:
 
 ```php
 namespace App\Exceptions;
 
 use GuzzleHttp\Exception\ClientException;
 use SMartins\Exceptions\Handlers\AbstractHandler;
+use SMartins\Exceptions\JsonApi\Error;
+use SMartins\Exceptions\JsonApi\Source;
+use SMartins\Exceptions\Response\ErrorHandledCollectionInterface;
+use SMartins\Exceptions\Response\ErrorHandledInterface;
 
 class GuzzleClientHandler extends AbstractHandler
 {
-    /**
-     * Create instance using the Exception to be handled.
-     *
-     * @param \GuzzleHttp\Exception\ClientException $e
-     */
     public function __construct(ClientException $e)
     {
         parent::__construct($e);
     }
-}
-```
-
-- You must implements the method `handle()` from `AbstractHandler` class. The method must return an instance of `Error` or `ErrorCollection`:
-
-```php
-namespace App\Exceptions;
-
-use SMartins\Exceptions\JsonAPI\Error;
-use SMartins\Exceptions\JsonAPI\Source;
-use GuzzleHttp\Exception\ClientException;
-use SMartins\Exceptions\Handlers\AbstractHandler;
 
-class GuzzleClientHandler extends AbstractHandler
-{
-    // ...
-
-    public function handle()
+    public function handle(): ErrorHandledInterface|ErrorHandledCollectionInterface
     {
-        return (new Error)->setStatus($this->getStatusCode())
-            ->setCode($this->getCode())
+        return (new Error)->setStatus((string) $this->getStatusCode())
+            ->setCode((string) $this->getCode())
             ->setSource((new Source())->setPointer($this->getDefaultPointer()))
             ->setTitle($this->getDefaultTitle())
             ->setDetail($this->exception->getMessage());
     }
 
-    public function getCode()
+    public function getCode(string $type = 'default'): int|string
     {
         // You can add a new type of code on `config/json-exception-handlers.php`
         return config('json-exception-handler.codes.client.default');
@@ -238,13 +213,17 @@ class GuzzleClientHandler extends AbstractHandler
 }
 ```
 
+- For returning multiple errors:
+
 ```php
 namespace App\Exceptions;
 
-use SMartins\Exceptions\JsonAPI\Error;
-use SMartins\Exceptions\JsonAPI\Source;
-use SMartins\Exceptions\JsonAPI\ErrorCollection;
+use SMartins\Exceptions\JsonApi\Error;
+use SMartins\Exceptions\JsonApi\Source;
+use SMartins\Exceptions\JsonApi\ErrorCollection;
 use SMartins\Exceptions\Handlers\AbstractHandler;
+use SMartins\Exceptions\Response\ErrorHandledCollectionInterface;
+use SMartins\Exceptions\Response\ErrorHandledInterface;
 
 class MyCustomizedHandler extends AbstractHandler
 {
@@ -253,14 +232,14 @@ class MyCustomizedHandler extends AbstractHandler
         parent::__construct($e);
     }
 
-    public function handle()
+    public function handle(): ErrorHandledInterface|ErrorHandledCollectionInterface
     {
-        $errors = (new ErrorCollection)->setStatusCode(400);
+        $errors = (new ErrorCollection)->setStatusCode('400');
 
         $exceptions = $this->exception->getExceptions();
 
         foreach ($exceptions as $exception) {
-            $error = (new Error)->setStatus(422)
+            $error = (new Error)->setStatus('422')
                 ->setSource((new Source())->setPointer($this->getDefaultPointer()))
                 ->setTitle($this->getDefaultTitle())
                 ->setDetail($exception->getMessage());
@@ -273,15 +252,15 @@ class MyCustomizedHandler extends AbstractHandler
 }
 ```
 
-- Now just registry your customized handler on `App\Exception\Handler` file on attribute `exceptionHandlers`. E.g:
+- Now just register your customized handler on `App\Exception\Handler` file on attribute `exceptionHandlers`. E.g:
 
 ```php
 namespace App\Exceptions;
 
-use Exception;
 use GuzzleHttp\Exception\ClientException;
 use Illuminate\Foundation\Exceptions\Handler as ExceptionHandler;
 use SMartins\Exceptions\JsonHandler;
+use Throwable;
 
 class Handler extends ExceptionHandler
 {
@@ -291,9 +270,18 @@ class Handler extends ExceptionHandler
         // Set on key the exception and on value the handler.
         ClientException::class => GuzzleClientHandler::class,
     ];
-
 ```
 
+## Upgrading from 2.x
+
+If you're upgrading from version 2.x, note the following changes:
+
+1. PHP 8.1+ is now required
+2. Laravel 10, 11, or 12 is required
+3. The `render()` method signature now uses `Throwable` instead of `Exception`
+4. All handler classes now use strict types and proper return type declarations
+5. Status codes are now always strings in the JSON response (as per JsonAPI spec)
+
 ## Response References:
 
 - http://jsonapi.org/format/#errors
diff --git a/composer.json b/composer.json
index 17a91b8..f84a343 100644
--- a/composer.json
+++ b/composer.json
@@ -11,7 +11,12 @@
         }
     ],
     "require": {
-        "php": ">=7.0.0"
+        "php": "^8.1",
+        "illuminate/support": "^10.0|^11.0|^12.0",
+        "illuminate/http": "^10.0|^11.0|^12.0",
+        "illuminate/validation": "^10.0|^11.0|^12.0",
+        "illuminate/database": "^10.0|^11.0|^12.0",
+        "illuminate/auth": "^10.0|^11.0|^12.0"
     },
     "autoload": {
         "psr-4": {
@@ -34,7 +39,9 @@
         }
     },
     "require-dev": {
-        "orchestra/testbench": "~3.0",
-        "phpunit/phpunit": "^7.1"
-    }
+        "orchestra/testbench": "^8.0|^9.0|^10.0",
+        "phpunit/phpunit": "^10.0|^11.0"
+    },
+    "minimum-stability": "stable",
+    "prefer-stable": true
 }
diff --git a/phpunit.xml b/phpunit.xml
index c31b987..13afc55 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -1,24 +1,23 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<phpunit bootstrap="vendor/autoload.php"
-         backupGlobals="false"
-         backupStaticAttributes="false"
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:noNamespaceSchemaLocation="vendor/phpunit/phpunit/phpunit.xsd"
+         bootstrap="vendor/autoload.php"
          colors="true"
-         verbose="true"
-         convertErrorsToExceptions="true"
-         convertNoticesToExceptions="true"
-         convertWarningsToExceptions="true"
-         processIsolation="false"
+         cacheDirectory=".phpunit.cache"
+         executionOrder="depends,defects"
+         failOnRisky="true"
+         failOnWarning="true"
          stopOnFailure="false">
     <testsuites>
         <testsuite name="Json Exception Handler">
             <directory>./tests/</directory>
         </testsuite>
     </testsuites>
-    <filter>
-        <whitelist>
+    <source>
+        <include>
             <directory suffix=".php">./src/</directory>
-        </whitelist>
-    </filter>
+        </include>
+    </source>
     <php>
         <env name="DB_CONNECTION" value="testing"/>
         <env name="APP_KEY" value="AckfSECXIvnK5r28GVIWUAxmbBSjTsmF"/>
diff --git a/src/Handlers/AbstractHandler.php b/src/Handlers/AbstractHandler.php
index 31508a2..b940f65 100644
--- a/src/Handlers/AbstractHandler.php
+++ b/src/Handlers/AbstractHandler.php
@@ -1,8 +1,9 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Handlers;
 
-use Exception;
 use Illuminate\Auth\Access\AuthorizationException;
 use Illuminate\Auth\AuthenticationException;
 use Illuminate\Database\Eloquent\ModelNotFoundException;
@@ -10,36 +11,36 @@
 use Illuminate\Validation\ValidationException;
 use InvalidArgumentException;
 use SMartins\Exceptions\JsonApi\Response as JsonApiResponse;
+use SMartins\Exceptions\Response\AbstractResponse;
 use SMartins\Exceptions\Response\ErrorHandledCollectionInterface;
 use SMartins\Exceptions\Response\ErrorHandledInterface;
 use Symfony\Component\HttpKernel\Exception\BadRequestHttpException;
 use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
+use Throwable;
 
 abstract class AbstractHandler
 {
     /**
      * The exception thrown.
-     *
-     * @var \Exception
      */
-    protected $exception;
+    protected Throwable $exception;
 
     /**
      * An array where the key is the class exception and the value is the handler
      * class that will treat the exception.
      *
-     * @var array
+     * @var array<class-string, class-string>
      */
-    protected $exceptionHandlers = [];
+    protected array $exceptionHandlers = [];
 
     /**
      * An internal array where the key is the exception class and the value is
      * the handler class that will treat the exception.
      *
-     * @var array
+     * @var array<class-string, class-string>
      */
-    protected $internalExceptionHandlers = [
-        Exception::class => Handler::class,
+    protected array $internalExceptionHandlers = [
+        Throwable::class => Handler::class,
         ModelNotFoundException::class => ModelNotFoundHandler::class,
         AuthenticationException::class => AuthenticationHandler::class,
         ValidationException::class => ValidationHandler::class,
@@ -51,11 +52,9 @@ abstract class AbstractHandler
     ];
 
     /**
-     * Create instance using the Exception to be handled.
-     *
-     * @param Exception $e
+     * Create instance using the Throwable to be handled.
      */
-    public function __construct(Exception $e)
+    public function __construct(Throwable $e)
     {
         $this->exception = $e;
     }
@@ -63,20 +62,16 @@ public function __construct(Exception $e)
     /**
      * Handle with an exception according to specific definitions. Returns one
      * or more errors using the exception from $exceptions attribute.
-     *
-     * @return ErrorHandledInterface|ErrorHandledCollectionInterface
      */
-    abstract public function handle();
+    abstract public function handle(): ErrorHandledInterface|ErrorHandledCollectionInterface;
 
     /**
      * Get error code. If code is empty from config file based on type.
-     *
-     * @param  string $type Code type from config file
-     * @return int
      */
-    public function getCode($type = 'default')
+    public function getCode(string $type = 'default'): int|string
     {
-        if (empty($code = $this->exception->getCode())) {
+        $code = $this->exception->getCode();
+        if (empty($code)) {
             return config('json-exception-handler.codes.'.$type);
         }
 
@@ -86,10 +81,9 @@ public function getCode($type = 'default')
     /**
      * Return response with handled exception.
      *
-     * @return \SMartins\Exceptions\Response\AbstractResponse
      * @throws \SMartins\Exceptions\Response\InvalidContentException
      */
-    public function handleException()
+    public function handleException(): AbstractResponse
     {
         $handler = $this->getExceptionHandler();
 
@@ -103,64 +97,55 @@ public function handleException()
     /**
      * Validate response from handle method of handler class.
      *
-     * @param ErrorHandledInterface|ErrorHandledCollectionInterface
-     * @return ErrorHandledCollectionInterface
-     *
      * @throws \SMartins\Exceptions\Response\InvalidContentException
      */
-    public function validatedHandledException($error)
+    public function validatedHandledException(ErrorHandledInterface|ErrorHandledCollectionInterface $error): ErrorHandledCollectionInterface
     {
         if ($error instanceof ErrorHandledCollectionInterface) {
             return $error->validatedContent(ErrorHandledInterface::class);
-        } elseif ($error instanceof ErrorHandledInterface) {
-            return $error->toCollection()->setStatusCode($error->getStatus());
         }
 
-        throw new InvalidArgumentException('The errors must be an instance of ['.ErrorHandledInterface::class.'] or ['.ErrorHandledCollectionInterface::class.'].');
+        return $error->toCollection()->setStatusCode($error->getStatus());
     }
 
     /**
      * Get the class the will handle the Exception from exceptionHandlers attributes.
-     *
-     * @return mixed
      */
-    public function getExceptionHandler()
+    public function getExceptionHandler(): self
     {
         $handlers = $this->getConfiguredHandlers();
 
-        $handler = isset($handlers[get_class($this->exception)])
-            ? $handlers[get_class($this->exception)]
-            : $this->getDefaultHandler();
+        $handler = $handlers[get_class($this->exception)] ?? $this->getDefaultHandler();
 
-        return new $handler($this->exception);
+        if (is_string($handler)) {
+            return new $handler($this->exception);
+        }
+
+        return $handler;
     }
 
     /**
      * Get exception handlers from internal and set on App\Exceptions\Handler.php.
      *
-     * @return array
+     * @return array<class-string, class-string>
      */
-    public function getConfiguredHandlers()
+    public function getConfiguredHandlers(): array
     {
         return array_merge($this->internalExceptionHandlers, $this->exceptionHandlers);
     }
 
     /**
      * Get default pointer using file and line of exception.
-     *
-     * @return string
      */
-    public function getDefaultPointer()
+    public function getDefaultPointer(): string
     {
         return '';
     }
 
     /**
      * Get default title from exception.
-     *
-     * @return string
      */
-    public function getDefaultTitle()
+    public function getDefaultTitle(): string
     {
         return Str::snake(class_basename($this->exception));
     }
@@ -168,10 +153,8 @@ public function getDefaultTitle()
     /**
      * Get default http code. Check if exception has getStatusCode() methods.
      * If not get from config file.
-     *
-     * @return int
      */
-    public function getStatusCode()
+    public function getStatusCode(): int
     {
         if (method_exists($this->exception, 'getStatusCode')) {
             return $this->exception->getStatusCode();
@@ -182,10 +165,8 @@ public function getStatusCode()
 
     /**
      * The default handler to handle not treated exceptions.
-     *
-     * @return \SMartins\Exceptions\Handlers\Handler
      */
-    public function getDefaultHandler()
+    public function getDefaultHandler(): self
     {
         return new Handler($this->exception);
     }
@@ -194,9 +175,9 @@ public function getDefaultHandler()
      * Get default response handler of the if any response handler was defined
      * on config file.
      *
-     * @return string
+     * @return class-string<AbstractResponse>
      */
-    public function getDefaultResponseHandler()
+    public function getDefaultResponseHandler(): string
     {
         return JsonApiResponse::class;
     }
@@ -204,11 +185,9 @@ public function getDefaultResponseHandler()
     /**
      * Get the response class that will handle the json response.
      *
-     * @todo Check if the response_handler on config is an instance of
-     *       \SMartins\Exceptions\Response\AbstractResponse
-     * @return string
+     * @return class-string<AbstractResponse>
      */
-    public function getResponseHandler()
+    public function getResponseHandler(): string
     {
         $response = config('json-exception-handler.response_handler');
 
@@ -218,10 +197,9 @@ public function getResponseHandler()
     /**
      * Set exception handlers.
      *
-     * @param array $handlers
-     * @return AbstractHandler
+     * @param  array<class-string, class-string>  $handlers
      */
-    public function setExceptionHandlers(array $handlers)
+    public function setExceptionHandlers(array $handlers): static
     {
         $this->exceptionHandlers = $handlers;
 
diff --git a/src/Handlers/AuthenticationHandler.php b/src/Handlers/AuthenticationHandler.php
index 1d0d1ac..55be86c 100644
--- a/src/Handlers/AuthenticationHandler.php
+++ b/src/Handlers/AuthenticationHandler.php
@@ -1,21 +1,34 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Handlers;
 
+use Illuminate\Auth\AuthenticationException;
 use SMartins\Exceptions\JsonApi\Error;
 use SMartins\Exceptions\JsonApi\Source;
+use SMartins\Exceptions\Response\ErrorHandledCollectionInterface;
+use SMartins\Exceptions\Response\ErrorHandledInterface;
+use Throwable;
 
 class AuthenticationHandler extends AbstractHandler
 {
     /**
-     * {@inheritdoc}
+     * @var AuthenticationException
      */
-    public function handle()
+    protected Throwable $exception;
+
+    public function __construct(AuthenticationException $e)
+    {
+        parent::__construct($e);
+    }
+
+    public function handle(): ErrorHandledInterface|ErrorHandledCollectionInterface
     {
-        return (new Error)->setStatus(401)
-            ->setCode($this->getCode('authentication'))
+        return (new Error)->setStatus('401')
+            ->setCode((string) $this->getCode('authentication'))
             ->setSource((new Source())->setPointer($this->getDefaultPointer()))
             ->setTitle($this->getDefaultTitle())
-            ->setDetail(__('exception::exceptions.authentication.detail'));
+            ->setDetail((string) __('exception::exceptions.authentication.detail'));
     }
 }
diff --git a/src/Handlers/AuthorizationHandler.php b/src/Handlers/AuthorizationHandler.php
index 0ff9b8f..0252be0 100644
--- a/src/Handlers/AuthorizationHandler.php
+++ b/src/Handlers/AuthorizationHandler.php
@@ -1,21 +1,34 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Handlers;
 
+use Illuminate\Auth\Access\AuthorizationException;
 use SMartins\Exceptions\JsonApi\Error;
 use SMartins\Exceptions\JsonApi\Source;
+use SMartins\Exceptions\Response\ErrorHandledCollectionInterface;
+use SMartins\Exceptions\Response\ErrorHandledInterface;
+use Throwable;
 
 class AuthorizationHandler extends AbstractHandler
 {
     /**
-     * {@inheritdoc}
+     * @var AuthorizationException
      */
-    public function handle()
+    protected Throwable $exception;
+
+    public function __construct(AuthorizationException $e)
+    {
+        parent::__construct($e);
+    }
+
+    public function handle(): ErrorHandledInterface|ErrorHandledCollectionInterface
     {
-        return (new Error)->setStatus(403)
-            ->setCode($this->getCode('authorization'))
+        return (new Error)->setStatus('403')
+            ->setCode((string) $this->getCode('authorization'))
             ->setSource((new Source())->setPointer($this->getDefaultPointer()))
-            ->setTitle(__('exception::exceptions.authorization.title'))
+            ->setTitle((string) __('exception::exceptions.authorization.title'))
             ->setDetail($this->exception->getMessage());
     }
 }
diff --git a/src/Handlers/BadRequestHttpHandler.php b/src/Handlers/BadRequestHttpHandler.php
index 9a3ffb5..fc70c29 100644
--- a/src/Handlers/BadRequestHttpHandler.php
+++ b/src/Handlers/BadRequestHttpHandler.php
@@ -1,19 +1,32 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Handlers;
 
 use SMartins\Exceptions\JsonApi\Error;
 use SMartins\Exceptions\JsonApi\Source;
+use SMartins\Exceptions\Response\ErrorHandledCollectionInterface;
+use SMartins\Exceptions\Response\ErrorHandledInterface;
+use Symfony\Component\HttpKernel\Exception\BadRequestHttpException;
+use Throwable;
 
 class BadRequestHttpHandler extends AbstractHandler
 {
     /**
-     * {@inheritdoc}
+     * @var BadRequestHttpException
      */
-    public function handle()
+    protected Throwable $exception;
+
+    public function __construct(BadRequestHttpException $e)
+    {
+        parent::__construct($e);
+    }
+
+    public function handle(): ErrorHandledInterface|ErrorHandledCollectionInterface
     {
-        return (new Error)->setStatus(400)
-            ->setCode($this->getCode('bad_request'))
+        return (new Error)->setStatus('400')
+            ->setCode((string) $this->getCode('bad_request'))
             ->setSource((new Source())->setPointer($this->getDefaultPointer()))
             ->setTitle($this->getDefaultTitle())
             ->setDetail($this->exception->getMessage());
diff --git a/src/Handlers/Handler.php b/src/Handlers/Handler.php
index d9ee00b..2312f43 100644
--- a/src/Handlers/Handler.php
+++ b/src/Handlers/Handler.php
@@ -1,19 +1,20 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Handlers;
 
 use SMartins\Exceptions\JsonApi\Error;
 use SMartins\Exceptions\JsonApi\Source;
+use SMartins\Exceptions\Response\ErrorHandledCollectionInterface;
+use SMartins\Exceptions\Response\ErrorHandledInterface;
 
 class Handler extends AbstractHandler
 {
-    /**
-     * {@inheritdoc}
-     */
-    public function handle()
+    public function handle(): ErrorHandledInterface|ErrorHandledCollectionInterface
     {
-        return (new Error)->setStatus($this->getStatusCode())
-            ->setCode($this->getCode())
+        return (new Error)->setStatus((string) $this->getStatusCode())
+            ->setCode((string) $this->getCode())
             ->setSource((new Source())->setPointer($this->getDefaultPointer()))
             ->setTitle($this->getDefaultTitle())
             ->setDetail($this->exception->getMessage());
diff --git a/src/Handlers/MissingScopeHandler.php b/src/Handlers/MissingScopeHandler.php
index 8819057..29152b6 100644
--- a/src/Handlers/MissingScopeHandler.php
+++ b/src/Handlers/MissingScopeHandler.php
@@ -1,19 +1,20 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Handlers;
 
 use SMartins\Exceptions\JsonApi\Error;
 use SMartins\Exceptions\JsonApi\Source;
+use SMartins\Exceptions\Response\ErrorHandledCollectionInterface;
+use SMartins\Exceptions\Response\ErrorHandledInterface;
 
 class MissingScopeHandler extends AbstractHandler
 {
-    /**
-     * {@inheritdoc}
-     */
-    public function handle()
+    public function handle(): ErrorHandledInterface|ErrorHandledCollectionInterface
     {
-        return (new Error)->setStatus(403)
-            ->setCode($this->getCode('missing_scope'))
+        return (new Error)->setStatus('403')
+            ->setCode((string) $this->getCode('missing_scope'))
             ->setSource((new Source())->setPointer($this->getDefaultPointer()))
             ->setTitle($this->getDefaultTitle())
             ->setDetail($this->exception->getMessage());
diff --git a/src/Handlers/ModelNotFoundHandler.php b/src/Handlers/ModelNotFoundHandler.php
index 4a24563..6dff20d 100644
--- a/src/Handlers/ModelNotFoundHandler.php
+++ b/src/Handlers/ModelNotFoundHandler.php
@@ -1,59 +1,60 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Handlers;
 
 use Illuminate\Database\Eloquent\ModelNotFoundException;
 use Illuminate\Support\Str;
 use SMartins\Exceptions\JsonApi\Error;
 use SMartins\Exceptions\JsonApi\Source;
+use SMartins\Exceptions\Response\ErrorHandledCollectionInterface;
+use SMartins\Exceptions\Response\ErrorHandledInterface;
+use Throwable;
 
 class ModelNotFoundHandler extends AbstractHandler
 {
     /**
      * @var ModelNotFoundException
      */
-    protected $exception;
+    protected Throwable $exception;
 
     /**
      * Create instance using the Exception to be handled.
-     *
-     * @param \Illuminate\Database\Eloquent\ModelNotFoundException $e
      */
     public function __construct(ModelNotFoundException $e)
     {
         parent::__construct($e);
     }
 
-    /**
-     * {@inheritdoc}
-     */
-    public function handle()
+    public function handle(): ErrorHandledInterface|ErrorHandledCollectionInterface
     {
         $entity = $this->extractEntityName($this->exception->getModel());
 
         $detail = __('exception::exceptions.model_not_found.title', ['model' => $entity]);
 
-        return (new Error)->setStatus(404)
-            ->setCode($this->getCode('model_not_found'))
+        return (new Error)->setStatus('404')
+            ->setCode((string) $this->getCode('model_not_found'))
             ->setSource((new Source())->setPointer('data/id'))
             ->setTitle(Str::snake(class_basename($this->exception)))
-            ->setDetail($detail);
+            ->setDetail((string) $detail);
     }
 
     /**
      * Get entity name based on model path to mount the message.
-     *
-     * @param  string $model
-     * @return string
      */
-    public function extractEntityName(string $model)
+    public function extractEntityName(?string $model): string
     {
-        $classNames = (array) explode('\\', $model);
+        if ($model === null) {
+            return 'Model';
+        }
+
+        $classNames = explode('\\', $model);
 
         $entityName = end($classNames);
 
         if ($this->entityHasTranslation($entityName)) {
-            return __('exception::exceptions.models.'.$entityName);
+            return (string) __('exception::exceptions.models.'.$entityName);
         }
 
         return $entityName;
@@ -62,28 +63,21 @@ public function extractEntityName(string $model)
     /**
      * Check if entity returned on ModelNotFoundException has translation on
      * exceptions file.
-     *
-     * @param  string $entityName The model name to check if has translation
-     * @return bool               Has translation or not
      */
     public function entityHasTranslation(string $entityName): bool
     {
-        $hasKey = in_array($entityName, $this->translationModelKeys());
-
-        if ($hasKey) {
-            return ! empty($hasKey);
-        }
-
-        return false;
+        return in_array($entityName, $this->translationModelKeys(), true);
     }
 
     /**
      * Get the models keys on exceptions lang file.
      *
-     * @return array An array with keys to translate
+     * @return array<int, string>
      */
     private function translationModelKeys(): array
     {
-        return array_keys(__('exception::exceptions.models'));
+        $models = __('exception::exceptions.models');
+
+        return is_array($models) ? array_keys($models) : [];
     }
 }
diff --git a/src/Handlers/NotFoundHttpHandler.php b/src/Handlers/NotFoundHttpHandler.php
index 9eae341..504c691 100644
--- a/src/Handlers/NotFoundHttpHandler.php
+++ b/src/Handlers/NotFoundHttpHandler.php
@@ -1,19 +1,32 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Handlers;
 
 use SMartins\Exceptions\JsonApi\Error;
 use SMartins\Exceptions\JsonApi\Source;
+use SMartins\Exceptions\Response\ErrorHandledCollectionInterface;
+use SMartins\Exceptions\Response\ErrorHandledInterface;
+use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
+use Throwable;
 
 class NotFoundHttpHandler extends AbstractHandler
 {
     /**
-     * {@inheritdoc}
+     * @var NotFoundHttpException
      */
-    public function handle()
+    protected Throwable $exception;
+
+    public function __construct(NotFoundHttpException $e)
+    {
+        parent::__construct($e);
+    }
+
+    public function handle(): ErrorHandledInterface|ErrorHandledCollectionInterface
     {
-        return (new Error)->setStatus($this->getStatusCode())
-            ->setCode($this->getCode('not_found_http'))
+        return (new Error)->setStatus((string) $this->getStatusCode())
+            ->setCode((string) $this->getCode('not_found_http'))
             ->setSource((new Source())->setPointer($this->getDefaultPointer()))
             ->setTitle($this->getDefaultTitle())
             ->setDetail($this->getNotFoundMessage());
@@ -21,17 +34,15 @@ public function handle()
 
     /**
      * Get message based on file. If file is RouteCollection return specific message.
-     *
-     * @return string
      */
-    public function getNotFoundMessage()
+    public function getNotFoundMessage(): string
     {
         $message = ! empty($this->exception->getMessage())
             ? $this->exception->getMessage()
             : class_basename($this->exception);
 
         if (basename($this->exception->getFile()) === 'RouteCollection.php') {
-            $message = __('exception::exceptions.not_found_http.message');
+            $message = (string) __('exception::exceptions.not_found_http.message');
         }
 
         return $message;
diff --git a/src/Handlers/OAuthServerHandler.php b/src/Handlers/OAuthServerHandler.php
index 9b752f0..95b84c0 100644
--- a/src/Handlers/OAuthServerHandler.php
+++ b/src/Handlers/OAuthServerHandler.php
@@ -1,30 +1,35 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Handlers;
 
 use League\OAuth2\Server\Exception\OAuthServerException;
 use SMartins\Exceptions\JsonApi\Error;
 use SMartins\Exceptions\JsonApi\Source;
+use SMartins\Exceptions\Response\ErrorHandledCollectionInterface;
+use SMartins\Exceptions\Response\ErrorHandledInterface;
+use Throwable;
 
 class OAuthServerHandler extends AbstractHandler
 {
+    /**
+     * @var OAuthServerException
+     */
+    protected Throwable $exception;
+
     /**
      * Create instance using the Exception to be handled.
-     *
-     * @param \League\OAuth2\Server\Exception\OAuthServerException $e
      */
     public function __construct(OAuthServerException $e)
     {
         parent::__construct($e);
     }
 
-    /**
-     * {@inheritdoc}
-     */
-    public function handle()
+    public function handle(): ErrorHandledInterface|ErrorHandledCollectionInterface
     {
-        return (new Error)->setStatus($this->getHttpStatusCode())
-            ->setCode($this->getCode())
+        return (new Error)->setStatus((string) $this->getStatusCode())
+            ->setCode((string) $this->getCode('oauth_server'))
             ->setSource((new Source())->setPointer($this->getDefaultPointer()))
             ->setTitle($this->exception->getErrorType())
             ->setDetail($this->exception->getMessage());
diff --git a/src/Handlers/ValidationHandler.php b/src/Handlers/ValidationHandler.php
index b22b3b2..90425f2 100644
--- a/src/Handlers/ValidationHandler.php
+++ b/src/Handlers/ValidationHandler.php
@@ -1,19 +1,32 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Handlers;
 
+use Illuminate\Validation\ValidationException;
 use SMartins\Exceptions\JsonApi\Error;
 use SMartins\Exceptions\JsonApi\ErrorCollection;
 use SMartins\Exceptions\JsonApi\Source;
+use SMartins\Exceptions\Response\ErrorHandledCollectionInterface;
+use SMartins\Exceptions\Response\ErrorHandledInterface;
+use Throwable;
 
 class ValidationHandler extends AbstractHandler
 {
     /**
-     * {@inheritdoc}
+     * @var ValidationException
      */
-    public function handle()
+    protected Throwable $exception;
+
+    public function __construct(ValidationException $e)
     {
-        $errors = (new ErrorCollection)->setStatusCode(422);
+        parent::__construct($e);
+    }
+
+    public function handle(): ErrorHandledInterface|ErrorHandledCollectionInterface
+    {
+        $errors = (new ErrorCollection)->setStatusCode('422');
 
         $failedFieldsRules = $this->getFailedFieldsRules();
 
@@ -22,13 +35,13 @@ public function handle()
                 $code = $this->getValidationCode($failedFieldsRules, $key, $field);
                 $title = $this->getValidationTitle($failedFieldsRules, $key, $field);
 
-                $error = (new Error)->setStatus(422)
+                $error = (new Error)->setStatus('422')
                     ->setSource((new Source())->setPointer($field))
                     ->setTitle($title ?? $this->getDefaultTitle())
                     ->setDetail($message);
 
                 if (! is_null($code)) {
-                    $error->setCode($code);
+                    $error->setCode((string) $code);
                 }
 
                 $errors->push($error);
@@ -40,13 +53,8 @@ public function handle()
 
     /**
      * Get the title of response based on rules and field getting from translations.
-     *
-     * @param  array $failedFieldsRules
-     * @param string $key
-     * @param string $field
-     * @return string|null
      */
-    public function getValidationTitle(array $failedFieldsRules, string $key, string $field)
+    public function getValidationTitle(array $failedFieldsRules, int $key, string $field): ?string
     {
         $title = __('exception::exceptions.validation.title', [
             'fails' => strtolower(array_keys($failedFieldsRules[$field])[$key]),
@@ -58,13 +66,8 @@ public function getValidationTitle(array $failedFieldsRules, string $key, string
 
     /**
      * Get the code of validation error from config.
-     *
-     * @param  array  $failedFieldsRules
-     * @param  string $key
-     * @param  string $field
-     * @return string|null
      */
-    public function getValidationCode(array $failedFieldsRules, string $key, string $field)
+    public function getValidationCode(array $failedFieldsRules, int $key, string $field): int|string|null
     {
         $rule = strtolower(array_keys($failedFieldsRules[$field])[$key]);
 
@@ -77,7 +80,7 @@ public function getValidationCode(array $failedFieldsRules, string $key, string
      * response object. If exception is generated by Validator::make() the
      * messages are get different.
      *
-     * @return array
+     * @return array<string, array<int, string>>
      */
     public function getFailedFieldsMessages(): array
     {
@@ -87,7 +90,7 @@ public function getFailedFieldsMessages(): array
     /**
      * Get the rules failed on fields.
      *
-     * @return array
+     * @return array<string, array<string, array<int, mixed>>>
      */
     public function getFailedFieldsRules(): array
     {
diff --git a/src/JsonApi/Error.php b/src/JsonApi/Error.php
index 7af2385..e81a094 100644
--- a/src/JsonApi/Error.php
+++ b/src/JsonApi/Error.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\JsonApi;
 
 use Illuminate\Contracts\Support\Arrayable;
@@ -7,77 +9,59 @@
 use SMartins\Exceptions\Response\ErrorHandledInterface;
 use SMartins\Exceptions\Traits\NotNullArrayable;
 
+/**
+ * @implements Arrayable<string, mixed>
+ */
 class Error implements Arrayable, ErrorHandledInterface
 {
     use NotNullArrayable;
 
     /**
      * A unique identifier for this particular occurrence of the problem.
-     *
-     * @var string
      */
-    protected $id;
+    protected ?string $id = null;
 
-    /**
-     * @var \SMartins\Exceptions\JsonApi\Links
-     */
-    protected $links;
+    protected ?Links $links = null;
 
     /**
      * The HTTP status code applicable to this problem, expressed as a string value.
-     *
-     * @var string
      */
-    protected $status;
+    protected ?string $status = null;
 
     /**
      * An application-specific error code, expressed as a string value.
-     *
-     * @var string
      */
-    protected $code;
+    protected ?string $code = null;
 
     /**
      * A short, human-readable summary of the problem that SHOULD NOT change from
      * occurrence to occurrence of the problem, except for purposes of localization.
-     *
-     * @var string
      */
-    protected $title;
+    protected ?string $title = null;
 
     /**
      * A human-readable explanation specific to this occurrence of the problem.
-     * Like title, this field’s value can be localized.
-     *
-     * @var string
+     * Like title, this field's value can be localized.
      */
-    protected $detail;
+    protected ?string $detail = null;
 
     /**
      * An object containing references to the source of the error.
-     *
-     * @var \SMartins\Exceptions\JsonApi\Source
      */
-    protected $source;
+    protected ?Source $source = null;
 
     /**
      * Get a unique identifier for this particular occurrence of the problem.
-     *
-     * @return string
      */
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
 
     /**
      * Set a unique identifier for this particular occurrence of the problem.
-     *
-     * @param string $id
-     *
-     * @return self
      */
-    public function setId(string $id): self
+    public function setId(string $id): static
     {
         $this->id = $id;
 
@@ -86,44 +70,31 @@ public function setId(string $id): self
 
     /**
      * Get the value of links.
-     *
-     * @return \SMartins\Exceptions\JsonApi\Links
      */
-    public function getLinks()
+    public function getLinks(): ?Links
     {
         return $this->links;
     }
 
     /**
      * Set the value of links.
-     *
-     * @param \SMartins\Exceptions\JsonApi\Links  $links
-     *
-     * @return self
      */
-    public function setLinks(Links $links): self
+    public function setLinks(Links $links): static
     {
         $this->links = $links;
 
         return $this;
     }
 
-    /**
-     * {@inheritdoc}
-     */
     public function getStatus(): string
     {
-        return $this->status;
+        return $this->status ?? '';
     }
 
     /**
      * Set the HTTP status code applicable to this problem, expressed as a string value.
-     *
-     * @param string $status
-     *
-     * @return self
      */
-    public function setStatus(string $status): self
+    public function setStatus(string $status): static
     {
         $this->status = $status;
 
@@ -132,22 +103,16 @@ public function setStatus(string $status): self
 
     /**
      * Get an application-specific error code, expressed as a string value.
-     *
-     * @return string
      */
-    public function getCode()
+    public function getCode(): ?string
     {
         return $this->code;
     }
 
     /**
      * Set an application-specific error code, expressed as a string value.
-     *
-     * @param string $code
-     *
-     * @return self
      */
-    public function setCode(string $code): self
+    public function setCode(string $code): static
     {
         $this->code = $code;
 
@@ -156,22 +121,16 @@ public function setCode(string $code): self
 
     /**
      * Get occurrence to occurrence of the problem, except for purposes of localization.
-     *
-     * @return string
      */
     public function getTitle(): string
     {
-        return $this->title;
+        return $this->title ?? '';
     }
 
     /**
      * Set occurrence to occurrence of the problem, except for purposes of localization.
-     *
-     * @param string $title
-     *
-     * @return self
      */
-    public function setTitle(string $title): self
+    public function setTitle(string $title): static
     {
         $this->title = $title;
 
@@ -179,23 +138,17 @@ public function setTitle(string $title): self
     }
 
     /**
-     * Get like title, this field’s value can be localized.
-     *
-     * @return string
+     * Get like title, this field's value can be localized.
      */
-    public function getDetail()
+    public function getDetail(): ?string
     {
         return $this->detail;
     }
 
     /**
-     * Set like title, this field’s value can be localized.
-     *
-     * @param string $detail
-     *
-     * @return self
+     * Set like title, this field's value can be localized.
      */
-    public function setDetail(string $detail): self
+    public function setDetail(string $detail): static
     {
         $this->detail = $detail;
 
@@ -204,31 +157,22 @@ public function setDetail(string $detail): self
 
     /**
      * Get an object containing references to the source of the error.
-     *
-     * @return \SMartins\Exceptions\JsonApi\Source
      */
-    public function getSource()
+    public function getSource(): ?Source
     {
         return $this->source;
     }
 
     /**
      * Set an object containing references to the source of the error.
-     *
-     * @param \SMartins\Exceptions\JsonApi\Source  $source
-     *
-     * @return self
      */
-    public function setSource(Source $source): self
+    public function setSource(Source $source): static
     {
         $this->source = $source;
 
         return $this;
     }
 
-    /**
-     * {@inheritdoc}
-     */
     public function toCollection(): ErrorHandledCollectionInterface
     {
         return new ErrorCollection([$this]);
diff --git a/src/JsonApi/ErrorCollection.php b/src/JsonApi/ErrorCollection.php
index 8efb248..6ded3d9 100644
--- a/src/JsonApi/ErrorCollection.php
+++ b/src/JsonApi/ErrorCollection.php
@@ -1,33 +1,34 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\JsonApi;
 
 use Illuminate\Support\Collection;
 use SMartins\Exceptions\Response\ErrorHandledCollectionInterface;
 use SMartins\Exceptions\Response\InvalidContentException;
 
+/**
+ * @extends Collection<int, Error>
+ */
 class ErrorCollection extends Collection implements ErrorHandledCollectionInterface
 {
     /**
      * The HTTP status code applicable to this problem, expressed as a string value.
-     *
-     * @var string
      */
-    protected $statusCode;
+    protected ?string $statusCode = null;
 
     /**
      * The HTTP headers on response.
      *
-     * @var array
+     * @var array<string, mixed>
      */
-    protected $headers = [];
+    protected array $headers = [];
 
     /**
      * Returns the status code.
-     *
-     * @return string|null
      */
-    public function getStatusCode()
+    public function getStatusCode(): ?string
     {
         return $this->statusCode;
     }
@@ -35,7 +36,7 @@ public function getStatusCode()
     /**
      * Returns response headers.
      *
-     * @return array headers
+     * @return array<string, mixed>
      */
     public function getHeaders(): array
     {
@@ -44,12 +45,8 @@ public function getHeaders(): array
 
     /**
      * Set the status code.
-     *
-     * @param string $statusCode
-     *
-     * @return self
      */
-    public function setStatusCode(string $statusCode)
+    public function setStatusCode(string $statusCode): static
     {
         $this->statusCode = $statusCode;
 
@@ -59,11 +56,9 @@ public function setStatusCode(string $statusCode)
     /**
      * Set the headers of response.
      *
-     * @param array $headers
-     *
-     * @return self
+     * @param  array<string, mixed>  $headers
      */
-    public function setHeaders(array $headers): self
+    public function setHeaders(array $headers): static
     {
         $this->headers = $headers;
 
@@ -71,7 +66,7 @@ public function setHeaders(array $headers): self
     }
 
     /**
-     * {@inheritdoc}
+     * @throws InvalidContentException
      */
     public function validatedContent(string $type): ErrorHandledCollectionInterface
     {
diff --git a/src/JsonApi/Links.php b/src/JsonApi/Links.php
index 218c951..0b6b456 100644
--- a/src/JsonApi/Links.php
+++ b/src/JsonApi/Links.php
@@ -1,18 +1,40 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\JsonApi;
 
+use Illuminate\Contracts\Support\Arrayable;
 use SMartins\Exceptions\Traits\NotNullArrayable;
 
-class Links
+/**
+ * @implements Arrayable<string, mixed>
+ */
+class Links implements Arrayable
 {
     use NotNullArrayable;
 
     /**
      * A link that leads to further details about this particular occurrence of
      * the problem.
-     *
-     * @var string
      */
-    protected $about;
+    protected ?string $about = null;
+
+    /**
+     * Get the about link.
+     */
+    public function getAbout(): ?string
+    {
+        return $this->about;
+    }
+
+    /**
+     * Set the about link.
+     */
+    public function setAbout(string $about): static
+    {
+        $this->about = $about;
+
+        return $this;
+    }
 }
diff --git a/src/JsonApi/Response.php b/src/JsonApi/Response.php
index 3e2351d..28cf878 100644
--- a/src/JsonApi/Response.php
+++ b/src/JsonApi/Response.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\JsonApi;
 
 use Illuminate\Http\JsonResponse;
@@ -9,8 +11,6 @@ class Response extends AbstractResponse
 {
     /**
      * Returns JSON response.
-     *
-     * @return \Illuminate\Http\JsonResponse
      */
     public function json(): JsonResponse
     {
diff --git a/src/JsonApi/Source.php b/src/JsonApi/Source.php
index dc7ea87..9cb0482 100644
--- a/src/JsonApi/Source.php
+++ b/src/JsonApi/Source.php
@@ -1,10 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\JsonApi;
 
 use Illuminate\Contracts\Support\Arrayable;
 use SMartins\Exceptions\Traits\NotNullArrayable;
 
+/**
+ * @implements Arrayable<string, mixed>
+ */
 class Source implements Arrayable
 {
     use NotNullArrayable;
@@ -13,36 +18,26 @@ class Source implements Arrayable
      * A JSON Pointer [RFC6901] to the associated entity in the request document
      * [e.g. "/data" for a primary data object, or "/data/attributes/title" for
      * a specific attribute].
-     *
-     * @var string
      */
-    protected $pointer;
+    protected ?string $pointer = null;
 
     /**
      * A string indicating which URI query parameter caused the error.
-     *
-     * @var string
      */
-    protected $parameter;
+    protected ?string $parameter = null;
 
     /**
      * Get pointer.
-     *
-     * @return  string
      */
-    public function getPointer()
+    public function getPointer(): ?string
     {
         return $this->pointer;
     }
 
     /**
      * Set pointer.
-     *
-     * @param  string  $pointer
-     *
-     * @return  self
      */
-    public function setPointer(string $pointer)
+    public function setPointer(string $pointer): static
     {
         $this->pointer = $pointer;
 
@@ -51,22 +46,16 @@ public function setPointer(string $pointer)
 
     /**
      * Get parameter.
-     *
-     * @return  string
      */
-    public function getParameter()
+    public function getParameter(): ?string
     {
         return $this->parameter;
     }
 
     /**
      * Set parameter.
-     *
-     * @param  string  $parameter
-     *
-     * @return  self
      */
-    public function setParameter(string $parameter)
+    public function setParameter(string $parameter): static
     {
         $this->parameter = $parameter;
 
diff --git a/src/JsonHandler.php b/src/JsonHandler.php
index af19e7c..3fc4509 100644
--- a/src/JsonHandler.php
+++ b/src/JsonHandler.php
@@ -1,7 +1,10 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions;
 
+use Illuminate\Http\JsonResponse;
 use SMartins\Exceptions\Handlers\Handler;
 use Throwable;
 
@@ -10,12 +13,8 @@ trait JsonHandler
     /**
      * Handle the json response. Check if exception is treated. If true call
      * the specific handler. If false set the default response to be returned.
-     *
-     * @param  \Throwable  $exception
-     *
-     * @return \Illuminate\Http\JsonResponse
      */
-    public function jsonResponse(Throwable $exception)
+    public function jsonResponse(Throwable $exception): JsonResponse
     {
         $handler = new Handler($exception);
 
diff --git a/src/JsonHandlerServiceProvider.php b/src/JsonHandlerServiceProvider.php
index 15436e3..272eda1 100644
--- a/src/JsonHandlerServiceProvider.php
+++ b/src/JsonHandlerServiceProvider.php
@@ -1,12 +1,14 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions;
 
 use Illuminate\Support\ServiceProvider;
 
 class JsonHandlerServiceProvider extends ServiceProvider
 {
-    public function boot()
+    public function boot(): void
     {
         $this->publishes([
             $this->configPath() => config_path('json-exception-handler.php'),
@@ -15,16 +17,16 @@ public function boot()
         $this->loadTranslationsFrom(__DIR__.'/../resources/lang', 'exception');
 
         $this->publishes([
-            __DIR__.'/../resources/lang' => resource_path('lang/vendor/exception'),
+            __DIR__.'/../resources/lang' => $this->app->langPath('vendor/exception'),
         ]);
     }
 
-    public function register()
+    public function register(): void
     {
         $this->mergeConfigFrom($this->configPath(), 'json-exception-handler');
     }
 
-    public function configPath()
+    public function configPath(): string
     {
         return __DIR__.'/../config/json-exception-handler.php';
     }
diff --git a/src/Response/AbstractResponse.php b/src/Response/AbstractResponse.php
index abf2657..320d3cf 100644
--- a/src/Response/AbstractResponse.php
+++ b/src/Response/AbstractResponse.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Response;
 
 use Illuminate\Http\JsonResponse;
@@ -8,22 +10,16 @@ abstract class AbstractResponse
 {
     /**
      * The HTTP status code.
-     *
-     * @var int
      */
-    protected $status;
+    protected int $status;
 
     /**
      * The errors on response.
-     *
-     * @var \SMartins\Exceptions\Response\ErrorHandledCollectionInterface
      */
-    protected $errors;
+    protected ErrorHandledCollectionInterface $errors;
 
     /**
      * Create new Response response passing the errors.
-     *
-     * @param \SMartins\Exceptions\Response\ErrorHandledCollectionInterface $errors
      */
     public function __construct(ErrorHandledCollectionInterface $errors)
     {
@@ -34,22 +30,16 @@ public function __construct(ErrorHandledCollectionInterface $errors)
 
     /**
      * Get the HTTP status code.
-     *
-     * @return  int
      */
-    public function getStatus()
+    public function getStatus(): int
     {
         return $this->status;
     }
 
     /**
      * Set the HTTP status code.
-     *
-     * @param  int  $status  The HTTP status code.
-     *
-     * @return  self
      */
-    public function setStatus(int $status)
+    public function setStatus(int $status): static
     {
         $this->status = $status;
 
@@ -58,18 +48,14 @@ public function setStatus(int $status)
 
     /**
      * Get the errors on response.
-     *
-     * @return \SMartins\Exceptions\Response\ErrorHandledCollectionInterface
      */
-    public function getErrors()
+    public function getErrors(): ErrorHandledCollectionInterface
     {
         return $this->errors;
     }
 
     /**
      * Returns JSON response.
-     *
-     * @return \Illuminate\Http\JsonResponse
      */
     abstract public function json(): JsonResponse;
 }
diff --git a/src/Response/ErrorCollectionInterface.php b/src/Response/ErrorCollectionInterface.php
index f30861d..bae6dca 100644
--- a/src/Response/ErrorCollectionInterface.php
+++ b/src/Response/ErrorCollectionInterface.php
@@ -1,31 +1,30 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Response;
 
 use Illuminate\Contracts\Support\Arrayable;
 
+/**
+ * @extends Arrayable<int, mixed>
+ */
 interface ErrorCollectionInterface extends Arrayable
 {
     /**
      * Returns response headers.
      *
-     * @return array Response headers
+     * @return array<string, mixed>
      */
-    public function getHeaders();
+    public function getHeaders(): array;
 
     /**
      * Set HTTP status code of response.
-     *
-     * @param string $statusCode
-     *
-     * @return static
      */
-    public function setStatusCode(string $statusCode);
+    public function setStatusCode(string $statusCode): static;
 
     /**
      * Get the HTTP status code.
-     *
-     * @return string|null
      */
-    public function getStatusCode();
+    public function getStatusCode(): ?string;
 }
diff --git a/src/Response/ErrorHandledCollectionInterface.php b/src/Response/ErrorHandledCollectionInterface.php
index 5541e92..d4dcfb3 100644
--- a/src/Response/ErrorHandledCollectionInterface.php
+++ b/src/Response/ErrorHandledCollectionInterface.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Response;
 
 interface ErrorHandledCollectionInterface extends ErrorCollectionInterface
@@ -9,10 +11,9 @@ interface ErrorHandledCollectionInterface extends ErrorCollectionInterface
      * $type parameter. If one item on collection was different of type an
      * exception is thrown.
      *
-     * @param  string $type
-     * @return self
+     * @param  class-string  $type
      *
-     * @throws \SMartins\Exceptions\Response\InvalidContentException
+     * @throws InvalidContentException
      */
     public function validatedContent(string $type): self;
 }
diff --git a/src/Response/ErrorHandledInterface.php b/src/Response/ErrorHandledInterface.php
index c7fa0e6..1dbdfe3 100644
--- a/src/Response/ErrorHandledInterface.php
+++ b/src/Response/ErrorHandledInterface.php
@@ -1,22 +1,18 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Response;
 
 interface ErrorHandledInterface
 {
     /**
      * Adds itself to a error collection and returns the instance of collection.
-     *
-     * @todo Maybe pass this method to another interface.
-     *
-     * @return \SMartins\Exceptions\Response\ErrorHandledCollectionInterface
      */
     public function toCollection(): ErrorHandledCollectionInterface;
 
     /**
      * Get the HTTP status code applicable to this problem, expressed as a string value.
-     *
-     * @return  string
      */
     public function getStatus(): string;
 }
diff --git a/src/Response/InvalidContentException.php b/src/Response/InvalidContentException.php
index ac908b0..5a3f5dd 100644
--- a/src/Response/InvalidContentException.php
+++ b/src/Response/InvalidContentException.php
@@ -1,8 +1,11 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Response;
 
-class InvalidContentException extends \Exception
+use Exception;
+
+class InvalidContentException extends Exception
 {
-    //
 }
diff --git a/src/Traits/NotNullArrayable.php b/src/Traits/NotNullArrayable.php
index 7b41c0d..59f73f1 100644
--- a/src/Traits/NotNullArrayable.php
+++ b/src/Traits/NotNullArrayable.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Traits;
 
 use Illuminate\Contracts\Support\Arrayable;
@@ -9,9 +11,9 @@ trait NotNullArrayable
     /**
      * Get the instance as an array.
      *
-     * @return array
+     * @return array<string, mixed>
      */
-    public function toArray()
+    public function toArray(): array
     {
         $array = [];
         foreach (get_object_vars($this) as $attribute => $value) {
diff --git a/tests/Feature/JsonHandlerTest.php b/tests/Feature/JsonHandlerTest.php
index 2ded966..f7df050 100644
--- a/tests/Feature/JsonHandlerTest.php
+++ b/tests/Feature/JsonHandlerTest.php
@@ -1,19 +1,22 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Tests\Feature;
 
 use Exception;
+use Illuminate\Auth\Access\AuthorizationException;
 use Illuminate\Http\Request;
 use Illuminate\Support\Facades\Route;
-use SMartins\Exceptions\Tests\TestCase;
 use Illuminate\Support\Facades\Validator;
-use Illuminate\Auth\Access\AuthorizationException;
+use PHPUnit\Framework\Attributes\Test;
 use SMartins\Exceptions\Tests\Fixtures\User as Model;
+use SMartins\Exceptions\Tests\TestCase;
 use Symfony\Component\HttpKernel\Exception\BadRequestHttpException;
 
 class JsonHandlerTest extends TestCase
 {
-    public function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -22,7 +25,7 @@ public function setUp()
         $this->setUpRoutes();
     }
 
-    public function setUpRoutes()
+    public function setUpRoutes(): void
     {
         Route::get('default_exception', function (Request $request) {
             throw new Exception('Test message', 1);
@@ -52,35 +55,40 @@ public function setUpRoutes()
         });
     }
 
-    public function testThrowsDefaultException()
+    #[Test]
+    public function testThrowsDefaultException(): void
     {
         $this->json('GET', 'default_exception')
             ->assertStatus(500)
             ->assertJsonStructure($this->defaultErrorStructure());
     }
 
-    public function testThrowsModelNotFoundException()
+    #[Test]
+    public function testThrowsModelNotFoundException(): void
     {
         $this->json('GET', 'model_not_found')
             ->assertStatus(404)
             ->assertJsonStructure($this->defaultErrorStructure());
     }
 
-    public function testThrowsAuthenticationException()
+    #[Test]
+    public function testThrowsAuthenticationException(): void
     {
         $this->json('GET', 'authentication')
             ->assertStatus(401)
             ->assertJsonStructure($this->defaultErrorStructure());
     }
 
-    public function testThrowsAuthorizationException()
+    #[Test]
+    public function testThrowsAuthorizationException(): void
     {
         $this->json('GET', 'authorization')
             ->assertStatus(403)
             ->assertJsonStructure($this->defaultErrorStructure());
     }
 
-    public function testThrowsValidationExceptions()
+    #[Test]
+    public function testThrowsValidationExceptions(): void
     {
         $params = ['email' => str_repeat('a', 11)];
 
@@ -89,14 +97,16 @@ public function testThrowsValidationExceptions()
             ->assertJsonStructure($this->defaultErrorStructure());
     }
 
-    public function testThrowsBadRequestHttpException()
+    #[Test]
+    public function testThrowsBadRequestHttpException(): void
     {
         $this->json('GET', 'bad_request')
             ->assertStatus(400)
             ->assertJsonStructure($this->defaultErrorStructure());
     }
 
-    public function testThrowsNotFoundHttpException()
+    #[Test]
+    public function testThrowsNotFoundHttpException(): void
     {
         $this->json('GET', 'not_found_route')
             ->assertStatus(404)
@@ -106,9 +116,9 @@ public function testThrowsNotFoundHttpException()
     /**
      * The default json response error structure.
      *
-     * @return array
+     * @return array<string, array<int, array<string, array<int, string>|string>>>
      */
-    public function defaultErrorStructure()
+    public function defaultErrorStructure(): array
     {
         return [
             'errors' => [[
@@ -116,7 +126,7 @@ public function defaultErrorStructure()
                 'code',
                 'title',
                 'detail',
-                'source' => ['pointer']
+                'source' => ['pointer'],
             ]],
         ];
     }
diff --git a/tests/Fixtures/Exceptions/Handler.php b/tests/Fixtures/Exceptions/Handler.php
index 5b5952e..f643c83 100644
--- a/tests/Fixtures/Exceptions/Handler.php
+++ b/tests/Fixtures/Exceptions/Handler.php
@@ -1,14 +1,18 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Tests\Fixtures\Exceptions;
 
-use Exception;
-use SMartins\Exceptions\JsonHandler;
 use Illuminate\Auth\Access\AuthorizationException;
-use SMartins\Exceptions\Handlers\NotFoundHttpHandler;
-use SMartins\Exceptions\Handlers\AuthorizationHandler;
 use Illuminate\Foundation\Exceptions\Handler as ExceptionHandler;
+use Illuminate\Http\Request;
+use SMartins\Exceptions\Handlers\AuthorizationHandler;
+use SMartins\Exceptions\Handlers\NotFoundHttpHandler;
+use SMartins\Exceptions\JsonHandler;
+use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
+use Throwable;
 
 class Handler extends ExceptionHandler
 {
@@ -18,7 +22,7 @@ class Handler extends ExceptionHandler
      * An array where the key is the class exception and the value is the handler
      * class that will treat the exception.
      *
-     * @var array
+     * @var array<class-string, class-string>
      */
     protected $exceptionHandlers = [
         AuthorizationException::class => AuthorizationHandler::class,
@@ -28,7 +32,7 @@ class Handler extends ExceptionHandler
     /**
      * A list of the exception types that are not reported.
      *
-     * @var array
+     * @var array<int, class-string<Throwable>>
      */
     protected $dontReport = [
         //
@@ -37,7 +41,7 @@ class Handler extends ExceptionHandler
     /**
      * A list of the inputs that are never flashed for validation exceptions.
      *
-     * @var array
+     * @var array<int, string>
      */
     protected $dontFlash = [
         'password',
@@ -46,28 +50,21 @@ class Handler extends ExceptionHandler
 
     /**
      * Report or log an exception.
-     *
-     * @param  \Exception  $exception
-     * @return void
      */
-    public function report(Exception $exception)
+    public function report(Throwable $e): void
     {
-        parent::report($exception);
+        parent::report($e);
     }
 
     /**
      * Render an exception into an HTTP response.
-     *
-     * @param  \Illuminate\Http\Request  $request
-     * @param  \Exception  $exception
-     * @return \Illuminate\Http\Response
      */
-    public function render($request, Exception $exception)
+    public function render($request, Throwable $e): Response
     {
         if ($request->expectsJson()) {
-            return $this->jsonResponse($exception);
+            return $this->jsonResponse($e);
         }
 
-        return parent::render($request, $exception);
+        return parent::render($request, $e);
     }
 }
diff --git a/tests/Fixtures/User.php b/tests/Fixtures/User.php
index 58f5e55..31d2555 100644
--- a/tests/Fixtures/User.php
+++ b/tests/Fixtures/User.php
@@ -1,10 +1,11 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Tests\Fixtures;
 
 use Illuminate\Database\Eloquent\Model;
 
 class User extends Model
 {
-
 }
diff --git a/tests/GettersAndSetters.php b/tests/GettersAndSetters.php
index 2614529..c9197be 100644
--- a/tests/GettersAndSetters.php
+++ b/tests/GettersAndSetters.php
@@ -1,16 +1,18 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Tests;
 
-use ReflectionClass;
 use InvalidArgumentException;
+use ReflectionClass;
 
 trait GettersAndSetters
 {
     /**
      * @throws \ReflectionException
      */
-    public function testGettersAndSetters()
+    public function testGettersAndSetters(): void
     {
         if (! property_exists($this, 'classToTest')) {
             throw new InvalidArgumentException('Please define the property $classToTest.');
diff --git a/tests/TestCase.php b/tests/TestCase.php
index 7496354..889160d 100644
--- a/tests/TestCase.php
+++ b/tests/TestCase.php
@@ -1,8 +1,11 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Tests;
 
 use Illuminate\Contracts\Debug\ExceptionHandler;
+use Illuminate\Foundation\Application;
 use Orchestra\Testbench\TestCase as BaseTestCase;
 use SMartins\Exceptions\JsonHandlerServiceProvider;
 use SMartins\Exceptions\Tests\Fixtures\Exceptions\Handler;
@@ -12,10 +15,9 @@ abstract class TestCase extends BaseTestCase
     /**
      * Define environment setup.
      *
-     * @param  \Illuminate\Foundation\Application  $app
-     * @return void
+     * @param  Application  $app
      */
-    protected function getEnvironmentSetUp($app)
+    protected function getEnvironmentSetUp($app): void
     {
         $app->singleton(
             ExceptionHandler::class,
@@ -25,12 +27,16 @@ protected function getEnvironmentSetUp($app)
         // Setup default database to use sqlite :memory:
         $app['config']->set('database.default', 'exceptions');
         $app['config']->set('database.connections.exceptions', [
-            'driver'   => 'sqlite',
+            'driver' => 'sqlite',
             'database' => ':memory:',
         ]);
     }
 
-    protected function getPackageProviders($app)
+    /**
+     * @param  Application  $app
+     * @return array<int, class-string>
+     */
+    protected function getPackageProviders($app): array
     {
         return [
             JsonHandlerServiceProvider::class,
diff --git a/tests/Unit/AbstractHandlerTest.php b/tests/Unit/AbstractHandlerTest.php
index 67acc67..f5a6344 100644
--- a/tests/Unit/AbstractHandlerTest.php
+++ b/tests/Unit/AbstractHandlerTest.php
@@ -1,34 +1,40 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Tests\Unit;
 
-use InvalidArgumentException;
-use SMartins\Exceptions\JsonApi\Error;
-use SMartins\Exceptions\Tests\TestCase;
+use Exception;
+use PHPUnit\Framework\Attributes\Test;
 use SMartins\Exceptions\Handlers\Handler;
-use SMartins\Exceptions\JsonApi\ErrorCollection;
+use SMartins\Exceptions\Tests\TestCase;
+use TypeError;
 
 class AbstractHandlerTest extends TestCase
 {
-    public function testShouldReturnsTheHandlerClassOnGetExceptionHandler()
+    #[Test]
+    public function testShouldReturnsTheHandlerClassOnGetExceptionHandler(): void
     {
-        $handler = new Handler(new \Exception);
+        $handler = new Handler(new Exception);
 
         $this->assertInstanceOf(Handler::class, $handler->getExceptionHandler());
     }
 
-    public function testGetDefaultHandler()
+    #[Test]
+    public function testGetDefaultHandler(): void
     {
-        $handler = new Handler(new \Exception);
+        $handler = new Handler(new Exception);
 
         $this->assertInstanceOf(Handler::class, $handler->getDefaultHandler());
     }
 
-    public function testValidateHandledExceptionWithInvalidArgument()
+    #[Test]
+    public function testValidateHandledExceptionWithInvalidArgument(): void
     {
-        $this->expectException(InvalidArgumentException::class);
+        $this->expectException(TypeError::class);
 
-        $handler = new Handler(new \Exception);
+        $handler = new Handler(new Exception);
+        // @phpstan-ignore-next-line
         $handler->validatedHandledException('invalid');
     }
 }
diff --git a/tests/Unit/ErrorCollectionTest.php b/tests/Unit/ErrorCollectionTest.php
index 0c48620..05bc7f2 100644
--- a/tests/Unit/ErrorCollectionTest.php
+++ b/tests/Unit/ErrorCollectionTest.php
@@ -1,14 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Tests\Unit;
 
-use SMartins\Exceptions\Tests\TestCase;
-use SMartins\Exceptions\Tests\GettersAndSetters;
+use PHPUnit\Framework\Attributes\Test;
 use SMartins\Exceptions\JsonApi\ErrorCollection;
+use SMartins\Exceptions\Tests\TestCase;
 
 class ErrorCollectionTest extends TestCase
 {
-    public function testSetHeaders()
+    #[Test]
+    public function testSetHeaders(): void
     {
         $error = new ErrorCollection;
         $this->assertInstanceOf(ErrorCollection::class, $error->setHeaders(['foo' => 'bar']));
diff --git a/tests/Unit/ErrorTest.php b/tests/Unit/ErrorTest.php
index 5e5b235..8287a26 100644
--- a/tests/Unit/ErrorTest.php
+++ b/tests/Unit/ErrorTest.php
@@ -1,59 +1,68 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Tests\Unit;
 
+use PHPUnit\Framework\Attributes\Test;
 use SMartins\Exceptions\JsonApi\Error;
+use SMartins\Exceptions\JsonApi\ErrorCollection;
 use SMartins\Exceptions\JsonApi\Links;
-use SMartins\Exceptions\Tests\TestCase;
 use SMartins\Exceptions\JsonApi\Source;
-use SMartins\Exceptions\JsonApi\ErrorCollection;
-use SMartins\Exceptions\Tests\GettersAndSetters;
+use SMartins\Exceptions\Tests\TestCase;
 
 class ErrorTest extends TestCase
 {
-    public function testGetAndSetId()
+    #[Test]
+    public function testGetAndSetId(): void
     {
         $error = new Error;
-        $this->assertInstanceOf(Error::class, $error->setId(1));
-        $this->assertEquals(1, $error->getId());
+        $this->assertInstanceOf(Error::class, $error->setId('1'));
+        $this->assertEquals('1', $error->getId());
     }
 
-    public function testGetAndSetLinks()
+    #[Test]
+    public function testGetAndSetLinks(): void
     {
         $error = new Error;
         $this->assertInstanceOf(Error::class, $error->setLinks($links = new Links));
         $this->assertEquals($links, $error->getLinks());
     }
 
-    public function testGetAndSetCode()
+    #[Test]
+    public function testGetAndSetCode(): void
     {
         $error = new Error;
-        $this->assertInstanceOf(Error::class, $error->setCode(1));
-        $this->assertEquals(1, $error->getCode());
+        $this->assertInstanceOf(Error::class, $error->setCode('1'));
+        $this->assertEquals('1', $error->getCode());
     }
 
-    public function testGetAndSetTitle()
+    #[Test]
+    public function testGetAndSetTitle(): void
     {
         $error = new Error;
         $this->assertInstanceOf(Error::class, $error->setTitle('tests'));
         $this->assertEquals('tests', $error->getTitle());
     }
 
-    public function testGetAndSetDetail()
+    #[Test]
+    public function testGetAndSetDetail(): void
     {
         $error = new Error;
         $this->assertInstanceOf(Error::class, $error->setDetail('detail'));
         $this->assertEquals('detail', $error->getDetail());
     }
 
-    public function testGetAndSerSource()
+    #[Test]
+    public function testGetAndSerSource(): void
     {
         $error = new Error;
         $this->assertInstanceOf(Error::class, $error->setSource($source = new Source));
         $this->assertEquals($source, $error->getSource());
     }
 
-    public function testToCollection()
+    #[Test]
+    public function testToCollection(): void
     {
         $error = new Error;
         $this->assertInstanceOf(ErrorCollection::class, $error->toCollection());
diff --git a/tests/Unit/HandlerTest.php b/tests/Unit/HandlerTest.php
index afe9d91..fa81d73 100644
--- a/tests/Unit/HandlerTest.php
+++ b/tests/Unit/HandlerTest.php
@@ -1,15 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Tests\Unit;
 
 use Exception;
+use PHPUnit\Framework\Attributes\Test;
+use SMartins\Exceptions\Handlers\Handler;
 use SMartins\Exceptions\JsonApi\Error;
 use SMartins\Exceptions\Tests\TestCase;
-use SMartins\Exceptions\Handlers\Handler;
 
 class HandlerTest extends TestCase
 {
-    public function testHandle()
+    #[Test]
+    public function testHandle(): void
     {
         $exception = new Exception('Test exception', 1);
 
diff --git a/tests/Unit/Handlers/ModelNotFoundHandlerTest.php b/tests/Unit/Handlers/ModelNotFoundHandlerTest.php
index d90358e..68f4858 100644
--- a/tests/Unit/Handlers/ModelNotFoundHandlerTest.php
+++ b/tests/Unit/Handlers/ModelNotFoundHandlerTest.php
@@ -1,18 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Tests\Unit\Handlers;
 
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\ModelNotFoundException;
+use PHPUnit\Framework\Attributes\Test;
 use SMartins\Exceptions\Handlers\ModelNotFoundHandler;
 use SMartins\Exceptions\Tests\TestCase;
 
 class ModelNotFoundHandlerTest extends TestCase
 {
-    /**
-     * @test
-     */
-    public function it_will_return_the_model_class_name_without_translations()
+    #[Test]
+    public function it_will_return_the_model_class_name_without_translations(): void
     {
         $exception = (new ModelNotFoundException())->setModel(NotTranslated::class);
 
@@ -20,7 +21,7 @@ public function it_will_return_the_model_class_name_without_translations()
 
         $error = $handler->handle();
 
-        $this->assertEquals(404, $error->getStatus());
+        $this->assertEquals('404', $error->getStatus());
         $this->assertEquals(
             'NotTranslated not found',
             $error->getDetail()
@@ -28,4 +29,6 @@ public function it_will_return_the_model_class_name_without_translations()
     }
 }
 
-class NotTranslated extends Model {}
+class NotTranslated extends Model
+{
+}
diff --git a/tests/Unit/SourceTest.php b/tests/Unit/SourceTest.php
index adf89e8..ec20cea 100644
--- a/tests/Unit/SourceTest.php
+++ b/tests/Unit/SourceTest.php
@@ -1,13 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 namespace SMartins\Exceptions\Tests\Unit;
 
-use SMartins\Exceptions\Tests\TestCase;
+use SMartins\Exceptions\JsonApi\Source;
 use SMartins\Exceptions\Tests\GettersAndSetters;
+use SMartins\Exceptions\Tests\TestCase;
 
 class SourceTest extends TestCase
 {
-    protected $classToTest = \SMartins\Exceptions\JsonApi\Source::class;
-
     use GettersAndSetters;
+
+    /**
+     * @var class-string
+     */
+    protected string $classToTest = Source::class;
 }