diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 06f9a3a..7790b32 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -6,22 +6,33 @@ jobs:
   test:
     runs-on: ubuntu-latest
 
+    strategy:
+      fail-fast: false
+      matrix:
+        php: ["8.3", "8.4"]
+        laravel: ["12.*", "13.*"]
+        include:
+          - laravel: "12.*"
+            testbench: "10.*"
+          - laravel: "13.*"
+            testbench: "11.*"
+
+    name: P${{ matrix.php }} - L${{ matrix.laravel }}
+
     steps:
-      # Step 1: Check out the repository
       - name: Checkout code
         uses: actions/checkout@v4
 
-      # Step 2: Set up PHP
       - name: Set up PHP
         uses: shivammathur/setup-php@v2
         with:
-          php-version: "8.2" # Set your desired PHP version
+          php-version: ${{ matrix.php }}
           extensions: mbstring, dom, zip
 
-      # Step 3: Install Composer dependencies
       - name: Install dependencies
-        run: composer install --no-interaction --prefer-dist
+        run: |
+          composer require "illuminate/support:${{ matrix.laravel }}" "orchestra/testbench:${{ matrix.testbench }}" --no-interaction --no-update
+          composer update --prefer-dist --no-interaction
 
-      # Step 4: Run PHPUnit tests
       - name: Run tests
         run: php ./vendor/bin/phpunit
diff --git a/README.md b/README.md
index dcef448..fe65350 100644
--- a/README.md
+++ b/README.md
@@ -259,6 +259,23 @@ Onym::make('document', 'pdf', 'hash', [
 Onym::hash(string $defaultFilename, string $extension, ?array $options = [])
 ```
 
+## Customizing the Default Separator
+
+When creating an Onym instance manually (outside the facade),
+you can customize the default separator used between filename parts.
+
+```php
+use Blaspsoft\Onym\Onym;
+
+// Create an instance with a custom default separator
+$onym = new Onym([], '|');
+
+// Use the timestamp strategy with the custom separator
+$filename = $onym->timestamp('invoice', 'pdf');
+
+// Result: "2024-03-15|invoice.pdf"
+```
+
 ## Global Configuration
 
 You can set default values for all strategies in your `config/onym.php` file:
@@ -270,7 +287,10 @@ return [
 
     // Default extension when none is provided
     'default_extension' => 'txt',
-
+    
+    // Default separator when none is provided
+    'default_separator' => '_',
+    
     // Default strategy when none is specified
     'strategy' => 'random',
 
@@ -314,6 +334,16 @@ return [
 
 These defaults can be overridden on a per-call basis using the `options` parameter in the `make()` and in all strategy methods.
 
+>⚠️ **Note:**  
+>If you have previously published the `config/onym.php` file, you need to manually add the new `default_separator` key:
+>
+>```php
+>'default_separator' => '_',
+>```
+>
+>Otherwise, the fallback separator `_` will still be used automatically by the package.
+
+
 ## License
 
 Blasp is open-sourced software licensed under the [MIT license](LICENSE).
diff --git a/composer.json b/composer.json
index ed38a76..b9a7fe1 100644
--- a/composer.json
+++ b/composer.json
@@ -17,11 +17,11 @@
   ],
   "require": {
     "php": "^8.0|^8.2|^8.3|^8.4",
-    "illuminate/support": "^8.0|^9.0|^10.0|^11.0|^12.0"
+    "illuminate/support": "^8.0|^9.0|^10.0|^11.0|^12.0|^13.0"
   },
   "require-dev": {
-    "orchestra/testbench": "^10.0",
-    "phpunit/phpunit": "^11.0"
+    "orchestra/testbench": "^10.0|^11.0",
+    "phpunit/phpunit": "^11.0|^12.0"
   },
   "autoload": {
     "psr-4": {
diff --git a/config/config.php b/config/config.php
index 082eab0..dab12dc 100644
--- a/config/config.php
+++ b/config/config.php
@@ -21,6 +21,15 @@
     */
     'default_extension' => 'txt',
 
+    /*
+    |--------------------------------------------------------------------------
+    | Onym Default Separator
+    |--------------------------------------------------------------------------
+    |
+    | Configure the default separator to use.
+    */
+    'default_separator' => '_',
+
     /*
     |--------------------------------------------------------------------------
     | Onym Generation Settings
diff --git a/src/Onym.php b/src/Onym.php
index 5303a5c..59eb7d5 100644
--- a/src/Onym.php
+++ b/src/Onym.php
@@ -45,12 +45,20 @@ class Onym
      */
     public string $defaultExtension;
 
-    public function __construct()
+    /**
+     * The default separator to use.
+     *
+     * @var string
+     */
+    public string $defaultSeparator;
+
+    public function __construct(array $options = [], ?string $defaultSeparator = null)
     {
         $this->strategy = config('onym.strategy', 'random');
-        $this->options = config('onym.options', []);
+        $this->options = $options ?: config('onym.options', []);
         $this->defaultFilename = config('onym.default_filename', 'file');
         $this->defaultExtension = config('onym.default_extension', 'txt');
+        $this->defaultSeparator = $defaultSeparator ?? config('onym.default_separator', '_');
     }
 
     /**
@@ -135,7 +143,8 @@ public function timestamp(string $defaultFilename, string $extension, ?array $op
 
         $format = $options['format'] ?? 'Y-m-d_H-i-s';
         $date = new DateTime();
-        $filename = $date->format($format) . '_' . $defaultFilename;
+        $separator = $options['separator'] ?? $this->defaultSeparator;
+        $filename = $date->format($format) . $separator . $defaultFilename;
         return $this->applyAffixes($filename, $extension, $options);
     }
 
@@ -152,7 +161,8 @@ public function date(string $defaultFilename, string $extension, ?array $options
         $options = $this->mergeOptions($options, 'date', $this->options);
         $format = $options['format'] ?? 'Y-m-d';
         $date = new DateTime();
-        $filename = $date->format($format) . '_' . $defaultFilename;
+        $separator = $options['separator'] ?? $this->defaultSeparator;
+        $filename = $date->format($format) . $separator . $defaultFilename;
         return $this->applyAffixes($filename, $extension, $options);
     }
 
@@ -168,7 +178,8 @@ public function numbered(string $defaultFilename, string $extension, ?array $opt
     {
         $options = $this->mergeOptions($options, 'numbered', $this->options);
         $number = $options['number'] ?? 1;
-        $filename = $defaultFilename . '_' . $number;
+        $separator = $options['separator'] ?? $this->defaultSeparator;
+        $filename = $defaultFilename . $separator . $number;
         return $this->applyAffixes($filename, $extension, $options);
     }
 
@@ -182,7 +193,8 @@ public function numbered(string $defaultFilename, string $extension, ?array $opt
     public function slug(string $defaultFilename, string $extension, ?array $options = [])
     {
         $options = $this->mergeOptions($options, 'slug', $this->options);
-        $filename = Str::slug($defaultFilename, $options['separator']);
+        $separator = $options['separator'] ?? $this->defaultSeparator;
+        $filename = Str::slug($defaultFilename, $separator);
         return $this->applyAffixes($filename, $extension, $options);
     }
 
diff --git a/tests/OnymTest.php b/tests/OnymTest.php
index 383dacf..9021824 100644
--- a/tests/OnymTest.php
+++ b/tests/OnymTest.php
@@ -210,4 +210,83 @@ public function it_allows_options_override_in_hash_method_with_null_values()
         $filename = $this->onym->hash('filename', 'txt', ['prefix' => null, 'suffix' => null, 'algorithm' => null]);
         $this->assertEquals($hash . '.txt', $filename);
     }
+
+    #[Test]
+    public function test_timestamp_uses_default_separator()
+    {
+        $onym = new Onym([], '|'); // Inject custom defaultSeparator
+        $result = $onym->timestamp('filename', 'txt');
+        $this->assertStringContainsString('|filename.txt', $result);
+    }
+
+    #[Test]
+    public function test_timestamp_overrides_separator_in_options()
+    {
+        $onym = new Onym([], '|');
+        $result = $onym->timestamp('filename', 'txt', ['separator' => '.']);
+        $this->assertStringContainsString('.filename.txt', $result);
+        $this->assertStringNotContainsString('|filename.txt', $result);
+    }
+
+    #[Test]
+    public function test_date_uses_default_separator()
+    {
+        $onym = new Onym([], '|');
+        $result = $onym->date('filename', 'txt');
+        $this->assertStringContainsString('|filename.txt', $result);
+    }
+
+    #[Test]
+    public function test_date_overrides_separator_in_options()
+    {
+        $onym = new Onym([], '|');
+        $result = $onym->date('filename', 'txt', ['separator' => '.']);
+        $this->assertStringContainsString('.filename.txt', $result);
+        $this->assertStringNotContainsString('|filename.txt', $result);
+    }
+
+    #[Test]
+    public function test_numbered_uses_default_separator()
+    {
+        $onym = new Onym([
+            'numbered' => ['prefix' => '', 'suffix' => '', 'number' => 5] // No separator defined!
+        ], '|');
+
+        $result = $onym->numbered('filename', 'txt');
+
+        $this->assertStringContainsString('|5.txt', $result);
+    }
+
+    #[Test]
+    public function test_numbered_overrides_separator_in_options()
+    {
+        $onym = new Onym([], '|');
+        $result = $onym->numbered('filename', 'txt', ['separator' => '-', 'number' => 5]);
+        $this->assertStringContainsString('-5.txt', $result);
+        $this->assertStringNotContainsString('|5.txt', $result);
+    }
+
+    #[Test]
+    public function test_slug_uses_default_separator()
+    {
+        $onym = new Onym([
+            'slug' => ['prefix' => '', 'suffix' => ''] // No separator defined!
+        ], '_');
+
+        $result = $onym->slug('My File Name', 'txt');
+
+        $this->assertStringContainsString('_', $result);
+        $this->assertStringNotContainsString('-', $result);
+        $this->assertStringEndsWith('.txt', $result);
+    }
+
+    #[Test]
+    public function test_slug_overrides_separator_in_options()
+    {
+        $onym = new Onym([], '_');
+        $result = $onym->slug('My File Name', 'txt', ['separator' => '.']);
+        $this->assertStringContainsString('.', $result);
+        $this->assertStringNotContainsString('_', $result);
+        $this->assertStringEndsWith('.txt', $result);
+    }
 }
\ No newline at end of file
diff --git a/tests/TestCase.php b/tests/TestCase.php
index c44b6ca..029d1dc 100644
--- a/tests/TestCase.php
+++ b/tests/TestCase.php
@@ -20,5 +20,6 @@ protected function getEnvironmentSetUp($app): void
         config()->set('onym.options', config('onym.options', []));
         config()->set('onym.default_filename', config('onym.default_filename', 'file'));
         config()->set('onym.default_extension', config('onym.default_extension', 'txt'));
+        config()->set('onym.default_separator', config('onym.default_separator', '_'));
     }
 }
\ No newline at end of file