diff --git a/README.md b/README.md
index 272b87a..98f6954 100644
--- a/README.md
+++ b/README.md
@@ -7,7 +7,6 @@
 ![GitHub](https://img.shields.io/github/license/toni-suarez/laravel-utm-parameter)
 [![Statamic Addon](https://img.shields.io/badge/https%3A%2F%2Fstatamic.com%2Faddons%2Ftoni-suarez%2Futm-parameter?style=flat-square&logo=statamic&logoColor=rgb(255%2C%2038%2C%20158)&label=Statamic&link=https%3A%2F%2Fstatamic.com%2Faddons%2Ftoni-suarez%2Futm-parameter)](https://statamic.com/addons/toni-suarez/utm-parameter)
 
-
 A lightweight way to handle UTM parameters session-based in your Laravel Application.
 
 ```blade
@@ -28,9 +27,14 @@ Open your terminal and navigate to your Laravel project directory. Then, use Com
 $ composer require suarez/laravel-utm-parameter
 ```
 
+Optionally, you can publish the config file of this package with this command:
+```bash
+php artisan vendor:publish --tag="utm-parameter"
+```
+
 ### Middleware Configuration
 
-Once the package is installed, you need to add the UtmParameters middleware to your Laravel application. Open the `bootstrap/app.php` file and append the `UtmParameters::class` inside the web-group.
+Once the package is installed, you can add the UtmParameters middleware to your Laravel application. Open the `bootstrap/app.php` file and append the `UtmParameters::class` inside the web-group.
 
 ```php
 # Laravel 11
@@ -45,33 +49,86 @@ return Application::configure(basePath: dirname(__DIR__))
   ...
 ```
 
-### Middleware Alias (Optional)
+Also, take a look at how to set an [alias for the middleware](https://github.com/toni-suarez/laravel-utm-parameter/wiki/Installation-Guide#step-3-alias-configuration-optional).
 
-To enable UTM-Parameters only for certain requests or routes in your application, you can add an alias for the UtmParameters middleware. Open the bootstrap/app.php file and append the `UtmParameters::class` inside the web-group.
+### Use as Facade
 
+If you prefer not to use it as middleware, you can utilize the UtmParameter Facade directly in your controllers or other parts of your application. Once the `boot($request)`-method is called, you have access to it at any place. For example:
 
 ```php
-# Laravel 11
-use Suarez\UtmParameter\Middleware\UtmParameters;
+use Suarez\UtmParameter\Facades\UtmParameter;
+
+// Inside a controller method
+class IndexController {
+  public function index(Request $request)
+  {
+      UtmParameter::boot($request);
+  }
+}
 
-->withMiddleware(function (Middleware $middleware) {
-    $middleware
-        ->alias([
-          /* ... keep the existing mappings here */
-          'utm-parameters' => UtmParameters::class,
-          ])
-        ->web(append: [
-          /* ... keep the existing mappings here */
-          UtmParameters::class
-        ]);
-})
+class SomeDifferentController {
+  public function index(Request $request)
+  {
+      $source = UtmParameter::get('source');
+  }
+}
 ```
 
-To apply UTM-Parameters to specific routes, use the following middleware: `utm-parameters`
+## Configuration
+
+The configuration file `config/utm-parameter.php` allows you to control the behavior of the UTM parameters handling.
 
 ```php
-Route::middleware('utm-parameters')
-  ->get('landing-page/{slug}', 'LandingPageController@show');
+<?php
+
+return [
+  /*
+   * Control Overwriting UTM Parameters (default: false)
+   *
+   * This setting determines how UTM parameters are handled within a user's session.
+   *
+   * - Enabled (true): New UTM parameters will overwrite existing ones during the session.
+   * - Disabled (false): The initial UTM parameters will persist throughout the session.
+   */
+  'override_utm_parameters' => false,
+
+  /*
+   * Session Key for UTM Parameters (default: 'utm')
+   *
+   * This key specifies the name used to access and store UTM parameters within the session data.
+   *
+   * If you're already using 'utm' for another purpose in your application,
+   * you can customize this key to avoid conflicts.
+   * Simply provide your preferred key name as a string value.
+   */
+  'session_key' => 'utm',
+
+  /*
+    * Allowed UTM Parameters (default: ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content', 'utm_campaign_id'])
+    *
+    * This setting defines the UTM parameters that are allowed within your application.
+    *
+    * In this array, you can specify a list of allowed UTM parameter names. Each parameter should be listed as a string.
+    * Only parameters from this list will be stored and processed in the session.
+    * and any parameter without the 'utm_' prefix will be ignored regardless of its inclusion in this list.
+    *
+    * Example: To only allow the basic UTM parameters (source, medium, and campaign), you could update the array like this:
+    *
+    * 'allowed_utm_parameters' => [
+    *     'utm_source',
+    *     'utm_medium',
+    *     'utm_campaign',
+    * ],
+    */
+    'allowed_utm_parameters' => [
+        'utm_source',
+        'utm_medium',
+        'utm_campaign',
+        'utm_term',
+        'utm_content',
+        'utm_campaign_id'
+    ],
+];
 ```
 
 ## Usage
@@ -142,6 +199,83 @@ Simply use:
  }
 ```
 
+### contains_utm()
+
+You can conditionally show or perform actions based on the presence or absence of a portion of an UTM parameters using contains.
+
+Simply use:
+- `contains_utm('source|medium|campaign|term|content', 'value')`
+- `contains_not_utm('source|medium|campaign|term|content', 'value')`
+
+```blade
+@containsUtm('campaign', 'weekly')
+  <div>Some Weekly related stuff</div>
+@endhasUtm
+
+@containsNotUtm('campaign', 'sales')
+  <p>Some not Sales stuff</p>
+@endhasNotUtm
+```
+
+```php
+ if (contains_utm('campaign', 'weekly')) {
+   redirect('to/special/page');
+ }
+
+ if (contains_not_utm('campaign', 'sale')) {
+   session()->flash('Did you know, we have a newsletter?');
+ }
+```
+
+## Extending the Middleware
+
+You can extend the middleware to customize the behavior of accepting UTM parameters. For example, you can override the `shouldAcceptUtmParameter` method.
+
+First, create a new middleware using Artisan:
+
+```bash
+php artisan make:middleware CustomMiddleware
+```
+
+Then, update the new middleware to extend UtmParameters and override the `shouldAcceptUtmParameter` method:
+
+```php
+<?php
+
+namespace App\Http\Middleware;
+
+use Illuminate\Http\Request;
+use Suarez\UtmParameter\Middleware\UtmParameters;
+
+class CustomMiddleware extends UtmParameters
+{
+    /**
+     * Determines whether the given request/response pair should accept UTM-Parameters.
+     *
+     * @param \Illuminate\Http\Request  $request
+     *
+     * @return bool
+     */
+    protected function shouldAcceptUtmParameter(Request $request)
+    {
+        return $request->isMethod('GET') || $request->isMethod('POST');
+    }
+}
+```
+
+Finally, update your `bootstrap/app.php` to use the CustomMiddleware:
+
+```php
+# bootstrap/app.php
+use App\Http\Middleware\CustomMiddleware;
+
+->withMiddleware(function (Middleware $middleware) {
+    $middleware->web(append: [
+        CustomMiddleware::class,
+        // other middleware...
+    ]);
+})
+```
 
 ## Resources
 Explore additional use cases and resources on the [wiki pages](https://github.com/toni-suarez/laravel-utm-parameter/wiki)
diff --git a/composer.json b/composer.json
index e52084b..36c8636 100644
--- a/composer.json
+++ b/composer.json
@@ -3,6 +3,13 @@
     "description": "A little helper to store and handle utm-parameter",
     "homepage": "https://github.com/toni-suarez/laravel-utm-parameter",
     "license": "MIT",
+    "keywords": [
+        "php",
+        "laravel",
+        "utm-parameter",
+        "social-media",
+        "utm"
+    ],
     "authors": [
         {
             "name": "Toni Suarez",
@@ -44,7 +51,10 @@
         "laravel": {
             "providers": [
                 "Suarez\\UtmParameter\\Providers\\UtmParameterServiceProvider"
-            ]
+            ],
+            "aliases": {
+                "UtmParameter": "Suarez\\UtmParameter\\Facades\\UtmParameter"
+            }
         }
     },
     "minimum-stability": "stable",
diff --git a/src/Facades/UtmParameter.php b/src/Facades/UtmParameter.php
new file mode 100644
index 0000000..ef7f39c
--- /dev/null
+++ b/src/Facades/UtmParameter.php
@@ -0,0 +1,26 @@
+<?php
+
+namespace Suarez\UtmParameter\Facades;
+
+use Illuminate\Support\Facades\Facade;
+
+/**
+ * @method static \Suarez\UtmParameter\UtmParameter boot(\Illuminate\Http\Request $request)
+ * @method static array useRequestOrSession(\Illuminate\Http\Request $request)
+ * @method static array all()
+ * @method static string|null get(string $key)
+ * @method static bool has(string $key, $value = null)
+ * @method static bool contains(string $key, string $value)
+ * @method static bool clear()
+ * @method static array getParameter(\Illuminate\Http\Request $request)
+ * @method static string ensureUtmPrefix(string $key)
+ *
+ * @see \Suarez\UtmParameter\UtmParameter
+ */
+class UtmParameter extends Facade
+{
+    protected static function getFacadeAccessor()
+    {
+        return \Suarez\UtmParameter\UtmParameter::class;
+    }
+}
diff --git a/src/Middleware/UtmParameters.php b/src/Middleware/UtmParameters.php
index 8b3dd60..7ff6eb2 100644
--- a/src/Middleware/UtmParameters.php
+++ b/src/Middleware/UtmParameters.php
@@ -4,7 +4,7 @@
 
 use Closure;
 use Illuminate\Http\Request;
-use Suarez\UtmParameter\UtmParameter;
+use Suarez\UtmParameter\Facades\UtmParameter;
 
 class UtmParameters
 {
@@ -19,7 +19,7 @@ class UtmParameters
     public function handle(Request $request, Closure $next)
     {
         if ($this->shouldAcceptUtmParameter($request)) {
-            app(UtmParameter::class)->boot(session('utm'));
+            UtmParameter::boot($request);
         }
 
         return $next($request);
diff --git a/src/Providers/UtmParameterServiceProvider.php b/src/Providers/UtmParameterServiceProvider.php
index 0063d52..37fccbf 100644
--- a/src/Providers/UtmParameterServiceProvider.php
+++ b/src/Providers/UtmParameterServiceProvider.php
@@ -4,6 +4,7 @@
 
 use Illuminate\Support\Facades\Blade;
 use Suarez\UtmParameter\UtmParameter;
+use Illuminate\Foundation\AliasLoader;
 use Illuminate\Support\ServiceProvider;
 
 class UtmParameterServiceProvider extends ServiceProvider
@@ -16,6 +17,7 @@ class UtmParameterServiceProvider extends ServiceProvider
     public function register()
     {
         $this->app->singleton(UtmParameter::class, fn () => new UtmParameter());
+        $this->mergeConfigFrom(__DIR__.'/../config/utm-parameter.php', 'utm-parameter');
     }
 
     /**
@@ -25,6 +27,8 @@ public function register()
      */
     public function boot()
     {
+        $this->publishes([__DIR__.'/../config/utm-parameter.php' => config_path('utm-parameter.php')], 'utm-parameter');
+
         Blade::if('hasUtm', function (string $key, string|null $value = null) {
             return has_utm($key, $value);
         });
@@ -32,5 +36,15 @@ public function boot()
         Blade::if('hasNotUtm', function (string $key, string|null $value = null) {
             return has_not_utm($key, $value);
         });
+
+        Blade::if('containsUtm', function (string $key, string|null $value = null) {
+            return contains_utm($key, $value);
+        });
+
+        Blade::if('containsNotUtm', function (string $key, string|null $value = null) {
+            return contains_not_utm($key, $value);
+        });
+
+        AliasLoader::getInstance()->alias('UtmParameter', \Suarez\UtmParameter\Facades\UtmParameter::class);
     }
 }
diff --git a/src/UtmParameter.php b/src/UtmParameter.php
index 75abced..7ca3879 100644
--- a/src/UtmParameter.php
+++ b/src/UtmParameter.php
@@ -2,6 +2,8 @@
 
 namespace Suarez\UtmParameter;
 
+use Illuminate\Http\Request;
+
 class UtmParameter
 {
     /**
@@ -9,30 +11,58 @@ class UtmParameter
      *
      * @var array
      */
-    public $parameters;
+    public array|null $parameters;
+
+    /**
+     * Utm Parameter Session Key.
+     *
+     * @var string
+     */
+    public string $sessionKey;
+
 
     public function __construct(array $parameters = [])
     {
+        $this->sessionKey = config('utm-parameter.session_key');
         $this->parameters = $parameters;
     }
 
     /**
      * Bootstrap UtmParameter.
      *
-     * @param array|string|null $parameters
+     * @param Request $request
      *
      * @return UtmParameter
      */
-    public function boot($parameters = null)
+    public function boot(Request $request)
     {
-        if (!$parameters) {
-            $parameters = self::getParameter();
-            session(['utm' => $parameters]);
+        $this->parameters = $this->useRequestOrSession($request);
+        return $this;
+    }
+
+    /**
+     * Check which Parameters should be used.
+     *
+     * @param \Illuminate\Http\Request $request
+     * @return array
+     */
+    public function useRequestOrSession(Request $request)
+    {
+        $currentRequestParameter = $this->getParameter($request);
+        $sessionParameter = session($this->sessionKey);
+
+        if (!empty($currentRequestParameter) && empty($sessionParameter)) {
+            session([$this->sessionKey => $currentRequestParameter]);
+            return $currentRequestParameter;
         }
 
-        $this->parameters = $parameters;
+        if (!empty($currentRequestParameter) && !empty($sessionParameter) && config('utm-parameter.override_utm_parameters')) {
+            $mergedParameters = array_merge($sessionParameter, $currentRequestParameter);
+            session([$this->sessionKey => $mergedParameters]);
+            return $mergedParameters;
+        }
 
-        return app(UtmParameter::class, $parameters);
+        return $sessionParameter;
     }
 
     /**
@@ -40,9 +70,9 @@ public function boot($parameters = null)
      *
      * @return array
      */
-    public static function all()
+    public function all()
     {
-        return app(UtmParameter::class)->parameters ?? [];
+        return $this->parameters ?? [];
     }
 
     /**
@@ -52,10 +82,10 @@ public static function all()
      *
      * @return string|null
      */
-    public static function get($key)
+    public function get(string $key)
     {
-        $parameters = self::all();
-        $key = self::ensureUtmPrefix($key);
+        $parameters = $this->all();
+        $key = $this->ensureUtmPrefix($key);
 
         if (!array_key_exists($key, $parameters)) {
             return null;
@@ -72,17 +102,17 @@ public static function get($key)
      *
      * @return bool
      */
-    public static function has($key, $value = null)
+    public function has(string $key, $value = null)
     {
-        $parameters = self::all();
-        $key = self::ensureUtmPrefix($key);
+        $parameters = $this->all();
+        $key = $this->ensureUtmPrefix($key);
 
         if (!array_key_exists($key, $parameters)) {
             return false;
         }
 
         if (array_key_exists($key, $parameters) && $value !== null) {
-            return self::get($key) === $value;
+            return $this->get($key) === $value;
         }
 
         return true;
@@ -95,16 +125,16 @@ public static function has($key, $value = null)
      * @param string $value
      * @return bool
      */
-    public static function contains($key, $value)
+    public function contains(string $key, string $value)
     {
-        $parameters = self::all();
-        $key = self::ensureUtmPrefix($key);
+        $parameters = $this->all();
+        $key = $this->ensureUtmPrefix($key);
 
         if (!array_key_exists($key, $parameters) || !is_string($value)) {
             return false;
         }
 
-        return str_contains(self::get($key), $value);
+        return str_contains($this->get($key), $value);
     }
 
     /**
@@ -112,10 +142,10 @@ public static function contains($key, $value)
      *
      * @return bool
      */
-    public static function clear()
+    public function clear()
     {
-        app(UtmParameter::class)->parameters = null;
-        session()->forget('utm');
+        session()->forget($this->sessionKey);
+        $this->parameters = null;
         return true;
     }
 
@@ -124,11 +154,18 @@ public static function clear()
      *
      * @return array
      */
-    protected static function getParameter()
+    protected static function getParameter(Request $request)
     {
-        return collect(request()->all())
+        $allowedKeys = config('utm-parameter.allowed_utm_parameters', [
+            'utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content'
+        ]);
+
+        return collect($request->all())
             ->filter(fn ($value, $key) => substr($key, 0, 4) === 'utm_')
-            ->map(fn ($value) => htmlspecialchars($value, ENT_QUOTES, 'UTF-8'))
+            ->filter(fn ($value, $key) => in_array($key, $allowedKeys))
+            ->mapWithKeys(fn ($value, $key) => [
+                htmlspecialchars($key, ENT_QUOTES, 'UTF-8') => htmlspecialchars($value, ENT_QUOTES, 'UTF-8')
+            ])
             ->toArray();
     }
 
@@ -138,7 +175,7 @@ protected static function getParameter()
      * @param string $key
      * @return string
      */
-    protected static function ensureUtmPrefix(string $key): string
+    protected function ensureUtmPrefix(string $key): string
     {
         return str_starts_with($key, 'utm_') ? $key : 'utm_' . $key;
     }
diff --git a/src/config/utm-parameter.php b/src/config/utm-parameter.php
new file mode 100644
index 0000000..0e5fb44
--- /dev/null
+++ b/src/config/utm-parameter.php
@@ -0,0 +1,50 @@
+<?php
+
+return [
+  /*
+   * Control Overwriting UTM Parameters (default: false)
+   *
+   * This setting determines how UTM parameters are handled within a user's session.
+   *
+   * - Enabled (true): New UTM parameters will overwrite existing ones during the session.
+   * - Disabled (false): The initial UTM parameters will persist throughout the session.
+   */
+  'override_utm_parameters' => false,
+
+  /*
+   * Session Key for UTM Parameters (default: 'utm')
+   *
+   * This key specifies the name used to access and store UTM parameters within the session data.
+   *
+   * If you're already using 'utm' for another purpose in your application,
+   * you can customize this key to avoid conflicts.
+   * Simply provide your preferred key name as a string value.
+   */
+  'session_key' => 'utm',
+
+  /*
+    * Allowed UTM Parameters (default: ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content', 'utm_campaign_id'])
+    *
+    * This setting defines the UTM parameters that are allowed within your application.
+    *
+    * In this array, you can specify a list of allowed UTM parameter names. Each parameter should be listed as a string.
+    * Only parameters from this list will be stored and processed in the session.
+    * and any parameter without the 'utm_' prefix will be ignored regardless of its inclusion in this list.
+    *
+    * Example: To only allow the basic UTM parameters (source, medium, and campaign), you could update the array like this:
+    *
+    * 'allowed_utm_parameters' => [
+    *     'utm_source',
+    *     'utm_medium',
+    *     'utm_campaign',
+    * ],
+    */
+    'allowed_utm_parameters' => [
+        'utm_source',
+        'utm_medium',
+        'utm_campaign',
+        'utm_term',
+        'utm_content',
+        'utm_campaign_id'
+    ],
+];
diff --git a/src/helper.php b/src/helper.php
index 1c61eb0..2bbf8c7 100644
--- a/src/helper.php
+++ b/src/helper.php
@@ -1,6 +1,6 @@
 <?php
 
-use Suarez\UtmParameter\UtmParameter;
+use Suarez\UtmParameter\Facades\UtmParameter;
 
 if (!function_exists('get_all_utm')) {
     function get_all_utm()
@@ -29,3 +29,18 @@ function has_not_utm($key, $value = null)
         return !UtmParameter::has($key, $value);
     }
 }
+
+
+if (!function_exists('contains_utm')) {
+    function contains_utm($key, $value)
+    {
+        return UtmParameter::contains($key, $value);
+    }
+}
+
+if (!function_exists('contains_not_utm')) {
+    function contains_not_utm($key, $value)
+    {
+        return !UtmParameter::contains($key, $value);
+    }
+}
diff --git a/tests/UtmParameterTest.php b/tests/UtmParameterTest.php
index 6e4bddc..1c96d79 100644
--- a/tests/UtmParameterTest.php
+++ b/tests/UtmParameterTest.php
@@ -2,14 +2,20 @@
 
 namespace Suarez\UtmParameter\Tests;
 
+use Illuminate\Http\Request;
 use Orchestra\Testbench\TestCase;
-use Suarez\UtmParameter\UtmParameter;
+use Suarez\UtmParameter\Facades\UtmParameter;
+use Illuminate\Support\Facades\Config;
 
 class UtmParameterTest extends TestCase
 {
+    protected $sessionKey;
     public function setUp(): void
     {
         parent::setUp();
+        Config::set('utm-parameter.override_utm_parameters', false);
+        Config::set('utm-parameter.session_key', 'custom_utm_key');
+        $this->sessionKey = Config::get('utm-parameter.session_key');
 
         $parameters = [
             'utm_source'   => 'google',
@@ -19,8 +25,19 @@ public function setUp(): void
             'utm_term'     => '{targetid}',
         ];
 
-        app()->singleton(UtmParameter::class, fn () => new UtmParameter());
-        app(UtmParameter::class)->boot($parameters);
+        $request = Request::create('/test', 'GET', $parameters);
+
+        UtmParameter::boot($request);
+    }
+
+    public function tearDown() : void
+    {
+        session()->forget($this->sessionKey);
+
+        Config::set('utm-parameter.override_utm_parameters', null);
+        Config::set('utm-parameter.session_key', null);
+
+        parent::tearDown();
     }
 
     public function test_it_should_be_bound_in_the_app()
@@ -29,6 +46,29 @@ public function test_it_should_be_bound_in_the_app()
         $this->assertInstanceOf(UtmParameter::class, $utm);
     }
 
+    public function test_it_should_have_a_session_key()
+    {
+        $this->assertIsString($this->sessionKey);
+    }
+
+    public function test_it_should_have_a_session()
+    {
+        $sessionContent = session($this->sessionKey);
+        $this->assertIsArray($sessionContent);
+        $this->assertArrayHasKey('utm_source', $sessionContent);
+        $this->assertIsNotString(session($this->sessionKey));
+    }
+
+    public function test_it_should_also_clear_a_session()
+    {
+        $sessionContent = session($this->sessionKey);
+        $this->assertIsArray($sessionContent);
+
+        $sessionEmptyContent = session()->forget($this->sessionKey);
+        $this->assertIsNotArray($sessionEmptyContent);
+        $this->assertNull($sessionEmptyContent);
+    }
+
     public function test_it_should_have_an_utm_attribute_bag()
     {
         $utm = UtmParameter::all();
@@ -41,6 +81,7 @@ public function test_it_should_have_a_source_parameter()
     {
         $source = UtmParameter::get('source');
         $this->assertNotEmpty($source);
+        $this->assertIsString($source);
         $this->assertEquals('google', $source);
     }
 
@@ -48,6 +89,7 @@ public function test_it_should_have_work_with_utm_inside_key()
     {
         $source = UtmParameter::get('utm_source');
         $this->assertNotEmpty($source);
+        $this->assertIsString($source);
         $this->assertEquals('google', $source);
     }
 
@@ -55,6 +97,7 @@ public function test_it_should_have_a_medium_parameter()
     {
         $medium = UtmParameter::get('medium');
         $this->assertNotEmpty($medium);
+        $this->assertIsString($medium);
         $this->assertEquals('cpc', $medium);
     }
 
@@ -62,6 +105,7 @@ public function test_it_should_have_a_campaign_parameter()
     {
         $campaign = UtmParameter::get('campaign');
         $this->assertNotEmpty($campaign);
+        $this->assertIsString($campaign);
         $this->assertEquals('{campaignid}', $campaign);
     }
 
@@ -69,6 +113,7 @@ public function test_it_should_have_a_content_parameter()
     {
         $content = UtmParameter::get('content');
         $this->assertNotEmpty($content);
+        $this->assertIsString($content);
         $this->assertEquals('{adgroupid}', $content);
     }
 
@@ -76,6 +121,7 @@ public function test_it_should_have_a_term_parameter()
     {
         $term = UtmParameter::get('term');
         $this->assertNotEmpty($term);
+        $this->assertIsString($term);
         $this->assertEquals('{targetid}', $term);
     }
 
@@ -83,6 +129,7 @@ public function test_it_should_get_a_utm_parameter_via_helper()
     {
         $source = get_utm('source');
         $this->assertNotEmpty($source);
+        $this->assertIsString($source);
         $this->assertEquals('google', $source);
     }
 
@@ -90,6 +137,7 @@ public function test_it_should_determine_if_utm_has_key()
     {
         $hasSource = UtmParameter::has('source');
         $this->assertIsBool($hasSource);
+        $this->assertNotEmpty($hasSource);
         $this->assertTrue($hasSource);
     }
 
@@ -97,6 +145,7 @@ public function test_it_should_determine_if_utm_has_not_key()
     {
         $hasRandomKey = UtmParameter::has('random-key');
         $this->assertIsBool($hasRandomKey);
+        $this->assertEmpty($hasRandomKey);
         $this->assertFalse($hasRandomKey);
     }
 
@@ -104,6 +153,7 @@ public function test_it_should_determine_if_utm_has_key_and_value()
     {
         $hasGoogleSource = UtmParameter::has('utm_source', 'google');
         $this->assertIsBool($hasGoogleSource);
+        $this->assertNotEmpty($hasGoogleSource);
         $this->assertTrue($hasGoogleSource);
     }
 
@@ -111,6 +161,7 @@ public function test_it_should_determine_if_utm_has_not_key_and_value()
     {
         $hasRandomSource = UtmParameter::has('random-source', 'random-value');
         $this->assertIsBool($hasRandomSource);
+        $this->assertEmpty($hasRandomSource);
         $this->assertFalse($hasRandomSource);
     }
 
@@ -118,6 +169,7 @@ public function test_it_should_determine_if_a_key_exists_for_utm_parameters()
     {
         $hasSource = has_utm('source');
         $this->assertIsBool($hasSource);
+        $this->assertNotEmpty($hasSource);
         $this->assertTrue($hasSource);
     }
 
@@ -125,6 +177,7 @@ public function test_it_should_determine_if_a_utm_parameter_equals_a_value()
     {
         $isGoogle = has_utm('source', 'google');
         $this->assertIsBool($isGoogle);
+        $this->assertNotEmpty($isGoogle);
         $this->assertTrue($isGoogle);
     }
 
@@ -132,6 +185,7 @@ public function test_it_should_determine_if_a_key_does_not_exists_for_utm_parame
     {
         $hasRandomKey = has_not_utm('random-key');
         $this->assertIsBool($hasRandomKey);
+        $this->assertNotEmpty($hasRandomKey);
         $this->assertTrue($hasRandomKey);
     }
 
@@ -139,6 +193,7 @@ public function test_it_should_determine_if_a_utm_parameter_not_equals_a_value()
     {
         $isRandomSource = has_not_utm('source', 'random');
         $this->assertIsBool($isRandomSource);
+        $this->assertNotEmpty($isRandomSource);
         $this->assertTrue($isRandomSource);
     }
 
@@ -146,6 +201,7 @@ public function test_it_should_determine_if_an_utm_contains_a_value()
     {
         $campaign = UtmParameter::contains('utm_campaign', 'campaign');
         $this->assertIsBool($campaign);
+        $this->assertNotEmpty($campaign);
         $this->assertTrue($campaign);
     }
 
@@ -153,35 +209,231 @@ public function test_it_should_determine_if_an_utm_contains_not_a_value()
     {
         $hasRandomCampaign = UtmParameter::contains('utm_campaign', 'some-thing');
         $this->assertIsBool($hasRandomCampaign);
+        $this->assertEmpty($hasRandomCampaign);
         $this->assertFalse($hasRandomCampaign);
     }
 
     public function test_it_should_determine_if_an_utm_contains_a_non_string_value()
     {
-        $campaign = UtmParameter::contains('utm_campaign', null);
+        $campaign = UtmParameter::contains('utm_campaign', 'null');
         $this->assertIsBool($campaign);
         $this->assertFalse($campaign);
 
-        $term = UtmParameter::contains('utm_term', false);
+        $term = UtmParameter::contains('utm_term', 'false');
         $this->assertIsBool($term);
         $this->assertFalse($term);
 
-        $content = UtmParameter::contains('utm_content', []);
+        $content = UtmParameter::contains('utm_content', '[]');
         $this->assertIsBool($content);
         $this->assertFalse($content);
 
-        $medium = UtmParameter::contains('utm_medium', 1);
+        $medium = UtmParameter::contains('utm_medium', '1');
         $this->assertIsBool($medium);
         $this->assertFalse($medium);
     }
 
+    public function test_it_should_determine_if_a_utm_parameter_contains_a_value()
+    {
+        $isGoogle = contains_utm('source', 'goog');
+        $this->assertIsBool($isGoogle);
+        $this->assertTrue($isGoogle);
+    }
+
+    public function test_it_should_determine_if_a_utm_parameter_not_contains_a_value()
+    {
+        $isRandomSource = has_not_utm('source', 'random');
+        $this->assertIsBool($isRandomSource);
+        $this->assertTrue($isRandomSource);
+    }
+
     public function test_it_should_clear_and_remove_the_utm_parameter_again()
     {
         $source = UtmParameter::get('source');
         $this->assertEquals('google', $source);
+        $this->assertArrayHasKey('utm_source', session($this->sessionKey));
 
         UtmParameter::clear();
         $emptySource = UtmParameter::get('source');
+        $this->assertNull(session($this->sessionKey));
         $this->assertNull($emptySource);
     }
+
+    public function test_it_should_overwrite_new_utm_parameter()
+    {
+        Config::set('utm-parameter.override_utm_parameters', true);
+
+        $source = UtmParameter::get('source');
+        $this->assertEquals('google', $source);
+
+        $parameters = [
+            'utm_source'   => 'newsletter',
+            'utm_medium'   => 'email'
+        ];
+
+        $request = Request::create('/', 'GET', $parameters);
+        UtmParameter::boot($request);
+
+        $source = UtmParameter::get('source');
+        $this->assertEquals('newsletter', $source);
+
+        $medium = UtmParameter::get('utm_medium');
+        $this->assertEquals('email', $medium);
+
+        $campaign = UtmParameter::get('campaign');
+        $this->assertEquals('{campaignid}', $campaign);
+    }
+
+    public function test_it_should_keep_existing_parameters()
+    {
+        Config::set('utm-parameter.override_utm_parameters', false);
+
+        $source = UtmParameter::get('source');
+        $this->assertEquals('google', $source);
+
+        $parameters = [
+            'id' => '0123456789',
+            'sorting' => 'relevance'
+        ];
+
+        $request = Request::create('/test', 'GET', $parameters);
+        UtmParameter::boot($request);
+
+        $id = UtmParameter::get('id');
+        $this->assertEmpty($id);
+        $this->assertNull($id);
+
+        $sorting = UtmParameter::get('sorting');
+        $this->assertEmpty($sorting);
+        $this->assertNull($sorting);
+
+        $source = UtmParameter::get('source');
+        $this->assertEquals('google', $source);
+
+        $medium = UtmParameter::get('utm_medium');
+        $this->assertEquals('cpc', $medium);
+
+        $campaign = UtmParameter::get('campaign');
+        $this->assertEquals('{campaignid}', $campaign);
+    }
+
+    public function test_it_should_keep_existing_parameters_while_browsing()
+    {
+        $source = UtmParameter::get('source');
+        $this->assertEquals('google', $source);
+
+        $parameters = ['id' => '0123456789', 'sorting' => 'relevance'];
+        $request = Request::create('/new-page', 'GET', $parameters);
+        UtmParameter::boot($request);
+
+        $id = UtmParameter::get('id');
+        $this->assertEmpty($id);
+        $this->assertNull($id);
+
+        $sorting = UtmParameter::get('sorting');
+        $this->assertEmpty($sorting);
+        $this->assertNull($sorting);
+
+        $source = UtmParameter::get('source');
+        $this->assertEquals('google', $source);
+
+        $parameters = [];
+        $request = Request::create('/second-page', 'GET', $parameters);
+        UtmParameter::boot($request);
+
+        $id = UtmParameter::get('id');
+        $this->assertEmpty($id);
+        $this->assertNull($id);
+
+        $sorting = UtmParameter::get('sorting');
+        $this->assertEmpty($sorting);
+        $this->assertNull($sorting);
+
+        $source = UtmParameter::get('source');
+        $this->assertEquals('google', $source);
+    }
+
+    public function test_it_should_only_use_utm_parameters_in_the_allowed_list()
+    {
+        session()->forget($this->sessionKey);
+        Config::set('utm-parameter.override_utm_parameters', true);
+        Config::set('utm-parameter.allowed_utm_parameters', ['utm_source', 'utm_medium']);
+
+        $parameters = [
+            'utm_source'=> 'newsletter',
+            'utm_medium' => 'email',
+            'utm_campaign' => 'not-allowed'
+        ];
+
+        $request = Request::create('/test', 'GET', $parameters);
+        UtmParameter::boot($request);
+
+        $source = UtmParameter::get('source');
+        $this->assertEquals('newsletter', $source);
+        $this->assertIsNotInt($source);
+        $this->assertNotEmpty($source);
+
+        $medium = UtmParameter::get('medium');
+        $this->assertEquals('email', $medium);
+        $this->assertIsNotInt($medium);
+        $this->assertNotEmpty($medium);
+
+        $campaign = UtmParameter::get('campaign');
+        $this->assertNull($campaign);
+        $this->assertEmpty($campaign);
+
+        $term = UtmParameter::get('term');
+        $this->assertNull($term);
+        $this->assertEmpty($term);
+
+        $utm_campaign_id = UtmParameter::get('utm_campaign_id');
+        $this->assertNull($utm_campaign_id);
+        $this->assertEmpty($utm_campaign_id);
+    }
+
+    public function test_it_should_sanitize_utm_parameter()
+    {
+        Config::set('utm-parameter.override_utm_parameters', true);
+
+        $parameters = [
+            'utm_source'=> '<span onclick="alert(\'alert\')">google</span>',
+            'utm_medium' => 'cpc<script>alert(1)</script>',
+            'utm_campaign' => '<script href="x" onload="alert(1)">',
+            'utm_content' => '<img src="x" onerror="alert(1)">',
+            'utm_term' => '%3Cscript%3Ealert(1)%3C%2Fscript%3E',
+            'utm_sql_injection' => '" OR 1=1; --',
+            'utm_html_tag' => '<b>bold</b>',
+            'utm_<html onclick="alert(\'alert\')">_tag' => '<b>bold</b>',
+            'utm_" OR 1=1; --' => '<b>bold</b>',
+        ];
+
+        $request = Request::create('/test', 'GET', $parameters);
+        UtmParameter::boot($request);
+
+        $source = UtmParameter::get('source');
+        $this->assertEquals('&lt;span onclick=&quot;alert(&#039;alert&#039;)&quot;&gt;google&lt;/span&gt;', $source);
+
+        $medium = UtmParameter::get('medium');
+        $this->assertEquals('cpc&lt;script&gt;alert(1)&lt;/script&gt;', $medium);
+
+        $campaign = UtmParameter::get('campaign');
+        $this->assertEquals('&lt;script href=&quot;x&quot; onload=&quot;alert(1)&quot;&gt;', $campaign);
+
+        $content = UtmParameter::get('content');
+        $this->assertEquals('&lt;img src=&quot;x&quot; onerror=&quot;alert(1)&quot;&gt;', $content);
+
+        $term = UtmParameter::get('term');
+        $this->assertEquals('%3Cscript%3Ealert(1)%3C%2Fscript%3E', $term);
+
+        $sql = UtmParameter::get('sql_injection');
+        $this->assertNull($sql);
+
+        $html = UtmParameter::get('html_tag');
+        $this->assertNull($html);
+
+        $randomKey = UtmParameter::get('utm_&lt;html onclick=&quot;alert(&#039;alert&#039;)&quot;&gt;_tag');
+        $this->assertNull($randomKey);
+
+        $randomSqlKey = UtmParameter::get('utm_&quot; OR 1=1; --');
+        $this->assertNull($randomSqlKey);
+    }
 }