diff --git a/src/Guardian.php b/src/Guardian.php
index 82e1fcd..e6b6777 100644
--- a/src/Guardian.php
+++ b/src/Guardian.php
@@ -15,6 +15,7 @@
 use Midnite81\Guardian\Exceptions\RulePreventsExecutionException;
 use Midnite81\Guardian\Helpers\Arrays;
 use Midnite81\Guardian\Helpers\RulesetPreparator;
+use Midnite81\Guardian\Helpers\Str;
 use Midnite81\Guardian\Rules\ErrorHandlingRule;
 use Midnite81\Guardian\Rules\RateLimitRule;
 use Midnite81\Guardian\Rulesets\GenericErrorHandlingRuleset;
@@ -124,7 +125,8 @@ public function setIdentifier(string $identifier, string $prefix = 'guardian'):
             throw new IdentifierCannotBeEmptyException('Identifier cannot be empty');
         }
 
-        $safe = preg_replace('/[^a-zA-Z0-9_-]/', '', $identifier);
+        $safe = preg_replace('/[^a-zA-Z0-9_-]/', '_', $identifier);
+        $safePrefix = preg_replace('/[^a-zA-Z0-9_-]/', '_', $prefix);
 
         if (empty($prefix)) {
             if (!preg_match('/^[a-zA-Z]/', $safe ?? '')) {
@@ -136,7 +138,12 @@ public function setIdentifier(string $identifier, string $prefix = 'guardian'):
             throw new IdentifierCannotBeEmptyException('Identifier cannot be empty');
         }
 
-        $this->identifier = ($prefix ? $prefix . '_' : '') . substr($safe, 0, 128);
+        $this->identifier = Str::of(($safePrefix ? $safePrefix . '_' : '') . substr($safe, 0, 128))
+            ->removeDuplicateCharacters('_')
+            ->removeFinalCharIf('_')
+            ->toLower()
+            ->limit(100)
+            ->toString();
     }
 
     /**
diff --git a/src/Helpers/Str.php b/src/Helpers/Str.php
new file mode 100644
index 0000000..a2d56c3
--- /dev/null
+++ b/src/Helpers/Str.php
@@ -0,0 +1,114 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Midnite81\Guardian\Helpers;
+
+/**
+ * Class Str
+ *
+ * A utility class for string manipulation operations.
+ *
+ * @internal This class is not part of the public API and may change without notice.
+ */
+class Str
+{
+    /**
+     * Constructor.
+     *
+     * @param string $string The initial string to manipulate.
+     */
+    public function __construct(protected string $string)
+    {
+    }
+
+    /**
+     * Create a new instance of Str with the given string.
+     *
+     * @param string $string The string to manipulate.
+     * @return Str
+     */
+    public static function of(string $string): Str
+    {
+        return new Str($string);
+    }
+
+    /**
+     * Get the current string value.
+     *
+     * @return string
+     */
+    public function toString(): string
+    {
+        return $this->string;
+    }
+
+    /**
+     * Convert the string to lowercase.
+     *
+     * @return $this
+     */
+    public function toLower(): Str
+    {
+        $this->string = strtolower($this->string);
+
+        return $this;
+    }
+
+    /**
+     * Remove duplicate occurrences of specified character(s).
+     *
+     * @param string|array<int, string> $characters The character(s) to remove duplicates of.
+     * @return $this
+     */
+    public function removeDuplicateCharacters(string|array $characters = []): Str
+    {
+        if (is_string($characters)) {
+            $characters = [$characters];
+        }
+
+        $pattern = '/(' . implode('|', array_map('preg_quote', $characters, array_fill(0, count($characters), '/'))) . ')\1+/u';
+        $this->string = (string) preg_replace($pattern, '$1', $this->string);
+
+        return $this;
+    }
+
+    /**
+     * Remove the final character if it matches the specified character.
+     *
+     * @param string $character The character to remove if it's at the end.
+     * @return $this
+     */
+    public function removeFinalCharIf(string $character): Str
+    {
+        $this->string = rtrim($this->string, '_');
+
+        return $this;
+    }
+
+    /**
+     * Limit the string to a specified number of characters.
+     *
+     * @param int $numberOfCharacters The maximum number of characters to keep.
+     * @return $this
+     */
+    public function limit(int $numberOfCharacters): Str
+    {
+        $this->string = substr($this->string, 0, $numberOfCharacters);
+
+        return $this;
+    }
+
+    /**
+     * Modify the string using a custom callback function.
+     *
+     * @param callable $callback A function that takes a string and returns a modified string.
+     * @return $this
+     */
+    public function modify(callable $callback): Str
+    {
+        $this->string = $callback($this->string);
+
+        return $this;
+    }
+}
diff --git a/tests/GuardianTest.php b/tests/GuardianTest.php
index bb90b8e..7db39da 100644
--- a/tests/GuardianTest.php
+++ b/tests/GuardianTest.php
@@ -232,13 +232,50 @@
         ->toThrow(IdentifierCannotBeEmptyException::class, 'Identifier cannot be empty');
 });
 
-it('must make safe an identifer starting with a number', function () {
+it('must make safe an identifier starting with a number', function () {
     $guardian = new Guardian('test', new LaravelStore(app('cache.store')));
 
     $guardian->setIdentifier('001', '');
     expect($guardian->getIdentifier())->toBe('id_001');
 });
 
+it('handles various identifier inputs', function () {
+    $guardian = new Guardian('test', new LaravelStore(app('cache.store')));
+
+    // Test with special characters
+    $guardian->setIdentifier('user@123_action/get');
+    expect($guardian->getIdentifier())->toBe('guardian_user_123_action_get');
+
+    // Test with spaces
+    $guardian->setIdentifier('user with spaces');
+    expect($guardian->getIdentifier())->toBe('guardian_user_with_spaces');
+
+    // Test with numbers only
+    $guardian->setIdentifier('12345');
+    expect($guardian->getIdentifier())->toBe('guardian_12345');
+
+    // Test with uppercase letters
+    $guardian->setIdentifier('USER_UPPERCASE');
+    expect($guardian->getIdentifier())->toBe('guardian_user_uppercase');
+
+    // Test with non-alphanumeric characters
+    $guardian->setIdentifier('user!@#$%^&*()');
+    expect($guardian->getIdentifier())->toBe('guardian_user');
+
+    // Test with leading and trailing spaces
+    $guardian->setIdentifier('  trimmed_user  ');
+    expect($guardian->getIdentifier())->toBe('guardian_trimmed_user');
+
+    // Test with very long identifier
+    $longIdentifier = str_repeat('a', 150);
+    $guardian->setIdentifier($longIdentifier);
+    expect($guardian->getIdentifier())->toBe('guardian_' . substr($longIdentifier, 0, 91));
+
+    // Test with a prefix
+    $guardian->setIdentifier('user', 'prefix/prefix');
+    expect($guardian->getIdentifier())->toBe('prefix_prefix_user');
+});
+
 it('throws exception by default when no error rules are set', function () {
     $guardian = new Guardian('test', new LaravelStore(app('cache.store')));
 
diff --git a/tests/Helpers/StrTest.php b/tests/Helpers/StrTest.php
new file mode 100644
index 0000000..47a8382
--- /dev/null
+++ b/tests/Helpers/StrTest.php
@@ -0,0 +1,60 @@
+<?php
+
+declare(strict_types=1);
+
+use Midnite81\Guardian\Helpers\Str;
+
+it('creates a new instance with a given string', function () {
+    $str = Str::of('Hello World');
+    expect($str)->toBeInstanceOf(Str::class);
+    expect($str->toString())->toBe('Hello World');
+});
+
+it('converts string to lowercase', function () {
+    $str = Str::of('HELLO WORLD');
+    expect($str->toLower()->toString())->toBe('hello world');
+});
+
+it('removes duplicate characters', function () {
+    $str = Str::of('aabbccddee');
+    expect($str->removeDuplicateCharacters(['a', 'b'])->toString())->toBe('abccddee');
+
+    $str = Str::of('aabbccddee');
+    expect($str->removeDuplicateCharacters('a')->toString())->toBe('abbccddee');
+
+    $str = Str::of('a__b__c__');
+    expect($str->removeDuplicateCharacters('_')->toString())->toBe('a_b_c_');
+});
+
+it('removes final character if it matches', function () {
+    $str = Str::of('Hello_');
+    expect($str->removeFinalCharIf('_')->toString())->toBe('Hello');
+
+    $str = Str::of('Hello');
+    expect($str->removeFinalCharIf('_')->toString())->toBe('Hello');
+});
+
+it('limits the string to specified number of characters', function () {
+    $str = Str::of('Hello World');
+    expect($str->limit(5)->toString())->toBe('Hello');
+
+    $str = Str::of('Hi');
+    expect($str->limit(5)->toString())->toBe('Hi');
+});
+
+it('modifies the string using a custom callback', function () {
+    $str = Str::of('hello world');
+    $result = $str->modify(function ($string) {
+        return strtoupper($string);
+    });
+    expect($result->toString())->toBe('HELLO WORLD');
+});
+
+it('chains multiple operations', function () {
+    $str = Str::of('HELLO__WORLD__');
+    $result = $str->toLower()
+        ->removeDuplicateCharacters('_')
+        ->removeFinalCharIf('_')
+        ->limit(10);
+    expect($result->toString())->toBe('hello_worl');
+});