diff --git a/app/Liquid/Filters/Data.php b/app/Liquid/Filters/Data.php
new file mode 100644
index 0000000..5b1f92f
--- /dev/null
+++ b/app/Liquid/Filters/Data.php
@@ -0,0 +1,22 @@
+<?php
+
+namespace App\Liquid\Filters;
+
+use Keepsuit\Liquid\Filters\FiltersProvider;
+
+/**
+ * Data filters for Liquid templates
+ */
+class Data extends FiltersProvider
+{
+    /**
+     * Convert a variable to JSON
+     *
+     * @param  mixed  $value  The variable to convert
+     * @return string JSON representation of the variable
+     */
+    public function json(mixed $value): string
+    {
+        return json_encode($value, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
+    }
+}
diff --git a/app/Liquid/Filters/Localization.php b/app/Liquid/Filters/Localization.php
new file mode 100644
index 0000000..c91c75b
--- /dev/null
+++ b/app/Liquid/Filters/Localization.php
@@ -0,0 +1,52 @@
+<?php
+
+namespace App\Liquid\Filters;
+
+use DateTimeInterface;
+use Illuminate\Support\Carbon;
+use Keepsuit\Liquid\Filters\FiltersProvider;
+
+/**
+ * Localization filters for Liquid templates
+ *
+ * Uses Laravel's translator for word translations. Translation files are located in the
+ * lang/{locale}/custom_plugins.php files.
+ */
+class Localization extends FiltersProvider
+{
+    /**
+     * Localize a date with strftime syntax
+     *
+     * @param  mixed  $date  The date to localize (string or DateTime)
+     * @param  string  $format  The strftime format string
+     * @param  string|null  $locale  The locale to use for localization
+     * @return string The localized date string
+     */
+    public function l_date(mixed $date, string $format = 'Y-m-d', ?string $locale = null): string
+    {
+        $carbon = $date instanceof DateTimeInterface ? Carbon::instance($date) : Carbon::parse($date);
+        if ($locale) {
+            $carbon->locale($locale);
+        }
+
+        return $carbon->translatedFormat($format);
+    }
+
+    /**
+     * Translate a common word to another language
+     *
+     * @param  string  $word  The word to translate
+     * @param  string  $locale  The locale to translate to
+     * @return string The translated word
+     */
+    public function l_word(string $word, string $locale): string
+    {
+        $translation = trans('custom_plugins.'.mb_strtolower($word), locale: $locale);
+
+        if ($translation === 'custom_plugins.'.mb_strtolower($word)) {
+            return $word;
+        }
+
+        return $translation;
+    }
+}
diff --git a/app/Liquid/Filters/Numbers.php b/app/Liquid/Filters/Numbers.php
new file mode 100644
index 0000000..53d1973
--- /dev/null
+++ b/app/Liquid/Filters/Numbers.php
@@ -0,0 +1,54 @@
+<?php
+
+namespace App\Liquid\Filters;
+
+use Illuminate\Support\Number;
+use Keepsuit\Liquid\Filters\FiltersProvider;
+
+class Numbers extends FiltersProvider
+{
+    /**
+     * Format a number with delimiters (default: comma)
+     *
+     * @param  mixed  $value  The number to format
+     * @param  string  $delimiter  The delimiter to use (default: comma)
+     * @param  string  $separator  The separator for decimal part (default: period)
+     */
+    public function number_with_delimiter(mixed $value, string $delimiter = ',', string $separator = '.'): string
+    {
+        // 2 decimal places for floats, 0 for integers
+        $decimal = is_float($value + 0) ? 2 : 0;
+
+        return number_format($value, decimals: $decimal, decimal_separator: $separator, thousands_separator: $delimiter);
+    }
+
+    /**
+     * Format a number as currency
+     *
+     * @param  mixed  $value  The number to format
+     * @param  string  $currency  Currency symbol or locale code
+     * @param  string  $delimiter  The delimiter to use (default: comma)
+     * @param  string  $separator  The separator for decimal part (default: period)
+     */
+    public function number_to_currency(mixed $value, string $currency = 'USD', string $delimiter = ',', string $separator = '.'): string
+    {
+        if ($currency === '$') {
+            $currency = 'USD';
+        } elseif ($currency === '€') {
+            $currency = 'EUR';
+        } elseif ($currency === '£') {
+            $currency = 'GBP';
+        }
+
+        if ($delimiter === '.' && $separator === ',') {
+            $locale = 'de';
+        } else {
+            $locale = 'en';
+        }
+
+        // 2 decimal places for floats, 0 for integers
+        $decimal = is_float($value + 0) ? 2 : 0;
+
+        return Number::currency($value, in: $currency, precision: $decimal, locale: $locale);
+    }
+}
diff --git a/app/Liquid/Filters/StringMarkup.php b/app/Liquid/Filters/StringMarkup.php
new file mode 100644
index 0000000..65fa7ed
--- /dev/null
+++ b/app/Liquid/Filters/StringMarkup.php
@@ -0,0 +1,61 @@
+<?php
+
+namespace App\Liquid\Filters;
+
+use Illuminate\Support\Facades\Log;
+use Illuminate\Support\Str;
+use Keepsuit\Liquid\Filters\FiltersProvider;
+use League\CommonMark\CommonMarkConverter;
+use League\CommonMark\Exception\CommonMarkException;
+
+/**
+ * String, Markup, and HTML filters for Liquid templates
+ */
+class StringMarkup extends FiltersProvider
+{
+    /**
+     * Pluralize a word based on count
+     *
+     * @param  string  $word  The word to pluralize
+     * @param  int  $count  The count to determine pluralization
+     * @return string The pluralized word with count
+     */
+    public function pluralize(string $word, int $count = 2): string
+    {
+        if ($count === 1) {
+            return "{$count} {$word}";
+        }
+
+        return "{$count} ".Str::plural($word, $count);
+    }
+
+    /**
+     * Convert markdown to HTML
+     *
+     * @param  string  $markdown  The markdown text to convert
+     * @return string The HTML representation of the markdown
+     */
+    public function markdown_to_html(string $markdown): ?string
+    {
+        $converter = new CommonMarkConverter();
+
+        try {
+            return $converter->convert($markdown);
+        } catch (CommonMarkException $e) {
+            Log::error('Markdown conversion error: '.$e->getMessage());
+        }
+
+        return null;
+    }
+
+    /**
+     * Strip HTML tags from a string
+     *
+     * @param  string  $html  The HTML string to strip
+     * @return string The string without HTML tags
+     */
+    public function strip_html(string $html): string
+    {
+        return strip_tags($html);
+    }
+}
diff --git a/app/Liquid/Filters/Uniqueness.php b/app/Liquid/Filters/Uniqueness.php
new file mode 100644
index 0000000..89148c4
--- /dev/null
+++ b/app/Liquid/Filters/Uniqueness.php
@@ -0,0 +1,43 @@
+<?php
+
+namespace App\Liquid\Filters;
+
+use Keepsuit\Liquid\Concerns\ContextAware;
+use Keepsuit\Liquid\Filters\FiltersProvider;
+
+/**
+ * Uniqueness filters for Liquid templates
+ */
+class Uniqueness extends FiltersProvider
+{
+    use ContextAware;
+
+    /**
+     * Append a random string to ensure uniqueness within a template
+     *
+     * @param  string  $prefix  The prefix to append the random string to
+     * @return string The prefix with a random string appended
+     */
+    public function append_random(string $prefix): string
+    {
+        return $prefix.$this->generateRandomString();
+    }
+
+    /**
+     * Generate a random string
+     *
+     * @param  int  $length  The length of the random string
+     * @return string A random string
+     */
+    private function generateRandomString(int $length = 4): string
+    {
+        $characters = 'abcdefghijklmnopqrstuvwxyz0123456789';
+        $randomString = '';
+
+        for ($i = 0; $i < $length; ++$i) {
+            $randomString .= $characters[rand(0, mb_strlen($characters) - 1)];
+        }
+
+        return $randomString;
+    }
+}
diff --git a/app/Models/Plugin.php b/app/Models/Plugin.php
index 1d07251..6c17101 100644
--- a/app/Models/Plugin.php
+++ b/app/Models/Plugin.php
@@ -2,6 +2,11 @@
 
 namespace App\Models;
 
+use App\Liquid\Filters\Data;
+use App\Liquid\Filters\Localization;
+use App\Liquid\Filters\Numbers;
+use App\Liquid\Filters\StringMarkup;
+use App\Liquid\Filters\Uniqueness;
 use Illuminate\Database\Eloquent\Factories\HasFactory;
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Support\Facades\App;
@@ -95,6 +100,14 @@ class Plugin extends Model
 
             if ($this->markup_language === 'liquid') {
                 $environment = App::make('liquid.environment');
+
+                // Register all custom filters
+                $environment->filterRegistry->register(Numbers::class);
+                $environment->filterRegistry->register(Data::class);
+                $environment->filterRegistry->register(StringMarkup::class);
+                $environment->filterRegistry->register(Uniqueness::class);
+                $environment->filterRegistry->register(Localization::class);
+
                 $template = $environment->parseString($this->render_markup);
                 $context = $environment->newRenderContext(data: ['size' => $size, 'data' => $this->data_payload]);
                 $renderedContent = $template->render($context);
diff --git a/lang/de/custom_plugins.php b/lang/de/custom_plugins.php
new file mode 100644
index 0000000..3fd8785
--- /dev/null
+++ b/lang/de/custom_plugins.php
@@ -0,0 +1,7 @@
+<?php
+
+return [
+    'today' => 'heute',
+    'tomorrow' => 'morgen',
+    'yesterday' => 'gestern',
+];
diff --git a/tests/Unit/Liquid/Filters/DataTest.php b/tests/Unit/Liquid/Filters/DataTest.php
new file mode 100644
index 0000000..ffb4088
--- /dev/null
+++ b/tests/Unit/Liquid/Filters/DataTest.php
@@ -0,0 +1,55 @@
+<?php
+
+use App\Liquid\Filters\Data;
+
+test('json filter converts arrays to JSON', function () {
+    $filter = new Data();
+    $array = ['foo' => 'bar', 'baz' => 'qux'];
+
+    expect($filter->json($array))->toBe('{"foo":"bar","baz":"qux"}');
+});
+
+test('json filter converts objects to JSON', function () {
+    $filter = new Data();
+    $object = new stdClass();
+    $object->foo = 'bar';
+    $object->baz = 'qux';
+
+    expect($filter->json($object))->toBe('{"foo":"bar","baz":"qux"}');
+});
+
+test('json filter handles nested structures', function () {
+    $filter = new Data();
+    $nested = [
+        'foo' => 'bar',
+        'nested' => [
+            'baz' => 'qux',
+            'items' => [1, 2, 3],
+        ],
+    ];
+
+    expect($filter->json($nested))->toBe('{"foo":"bar","nested":{"baz":"qux","items":[1,2,3]}}');
+});
+
+test('json filter handles scalar values', function () {
+    $filter = new Data();
+
+    expect($filter->json('string'))->toBe('"string"');
+    expect($filter->json(123))->toBe('123');
+    expect($filter->json(true))->toBe('true');
+    expect($filter->json(null))->toBe('null');
+});
+
+test('json filter preserves unicode characters', function () {
+    $filter = new Data();
+    $data = ['message' => 'Hello, 世界'];
+
+    expect($filter->json($data))->toBe('{"message":"Hello, 世界"}');
+});
+
+test('json filter does not escape slashes', function () {
+    $filter = new Data();
+    $data = ['url' => 'https://example.com/path'];
+
+    expect($filter->json($data))->toBe('{"url":"https://example.com/path"}');
+});
diff --git a/tests/Unit/Liquid/Filters/LocalizationTest.php b/tests/Unit/Liquid/Filters/LocalizationTest.php
new file mode 100644
index 0000000..384c837
--- /dev/null
+++ b/tests/Unit/Liquid/Filters/LocalizationTest.php
@@ -0,0 +1,62 @@
+<?php
+
+use App\Liquid\Filters\Localization;
+
+test('l_date formats date with default format', function () {
+    $filter = new Localization();
+    $date = '2025-01-11';
+
+    $result = $filter->l_date($date);
+
+    // Default format is 'Y-m-d', which should output something like '2025-01-11'
+    // The exact output might vary depending on the locale, but it should contain the year, month, and day
+    expect($result)->toContain('2025');
+    expect($result)->toContain('01');
+    expect($result)->toContain('11');
+});
+
+test('l_date formats date with custom format', function () {
+    $filter = new Localization();
+    $date = '2025-01-11';
+
+    $result = $filter->l_date($date, '%y %b');
+
+    // Format '%y %b' should output something like '25 Jan'
+    // The month name might vary depending on the locale
+    expect($result)->toContain('25');
+    // We can't check for 'Jan' specifically as it might be localized
+});
+
+test('l_date handles DateTime objects', function () {
+    $filter = new Localization();
+    $date = new DateTimeImmutable('2025-01-11');
+
+    $result = $filter->l_date($date, 'Y-m-d');
+
+    expect($result)->toContain('2025-01-11');
+});
+
+test('l_word translates common words', function () {
+    $filter = new Localization();
+
+    expect($filter->l_word('today', 'de'))->toBe('heute');
+});
+
+test('l_word returns original word if no translation exists', function () {
+    $filter = new Localization();
+
+    expect($filter->l_word('hello', 'es-ES'))->toBe('hello');
+    expect($filter->l_word('world', 'ko'))->toBe('world');
+});
+
+test('l_word is case-insensitive', function () {
+    $filter = new Localization();
+
+    expect($filter->l_word('TODAY', 'de'))->toBe('heute');
+});
+
+test('l_word returns original word for unknown locales', function () {
+    $filter = new Localization();
+
+    expect($filter->l_word('today', 'unknown-locale'))->toBe('today');
+});
diff --git a/tests/Unit/Liquid/Filters/NumbersTest.php b/tests/Unit/Liquid/Filters/NumbersTest.php
new file mode 100644
index 0000000..8ea73bf
--- /dev/null
+++ b/tests/Unit/Liquid/Filters/NumbersTest.php
@@ -0,0 +1,47 @@
+<?php
+
+use App\Liquid\Filters\Numbers;
+
+test('number_with_delimiter formats numbers with commas by default', function () {
+    $filter = new Numbers();
+
+    expect($filter->number_with_delimiter(1234))->toBe('1,234');
+    expect($filter->number_with_delimiter(1000000))->toBe('1,000,000');
+    expect($filter->number_with_delimiter(0))->toBe('0');
+});
+
+test('number_with_delimiter handles custom delimiters', function () {
+    $filter = new Numbers();
+
+    expect($filter->number_with_delimiter(1234, '.'))->toBe('1.234');
+    expect($filter->number_with_delimiter(1000000, ' '))->toBe('1 000 000');
+});
+
+test('number_with_delimiter handles decimal values with custom separators', function () {
+    $filter = new Numbers();
+
+    expect($filter->number_with_delimiter(1234.57, ' ', ','))->toBe('1 234,57');
+    expect($filter->number_with_delimiter(1234.5, '.', ','))->toBe('1.234,50');
+});
+
+test('number_to_currency formats numbers with dollar sign by default', function () {
+    $filter = new Numbers();
+
+    expect($filter->number_to_currency(1234))->toBe('$1,234');
+    expect($filter->number_to_currency(1234.5))->toBe('$1,234.50');
+    expect($filter->number_to_currency(0))->toBe('$0');
+});
+
+test('number_to_currency handles custom currency symbols', function () {
+    $filter = new Numbers();
+
+    expect($filter->number_to_currency(1234, '£'))->toBe('£1,234');
+    expect($filter->number_to_currency(152350.69, '€'))->toBe('€152,350.69');
+});
+
+test('number_to_currency handles custom delimiters and separators', function () {
+    $filter = new Numbers();
+
+    expect($filter->number_to_currency(1234.57, '£', '.', ','))->toBe('1.234,57 £');
+    expect($filter->number_to_currency(1234.57, '€', ',', '.'))->toBe('€1,234.57');
+});
diff --git a/tests/Unit/Liquid/Filters/StringMarkupTest.php b/tests/Unit/Liquid/Filters/StringMarkupTest.php
new file mode 100644
index 0000000..4021a07
--- /dev/null
+++ b/tests/Unit/Liquid/Filters/StringMarkupTest.php
@@ -0,0 +1,90 @@
+<?php
+
+use App\Liquid\Filters\StringMarkup;
+
+test('pluralize returns singular form with count 1', function () {
+    $filter = new StringMarkup();
+
+    expect($filter->pluralize('book', 1))->toBe('1 book');
+    expect($filter->pluralize('person', 1))->toBe('1 person');
+});
+
+test('pluralize returns plural form with count greater than 1', function () {
+    $filter = new StringMarkup();
+
+    expect($filter->pluralize('book', 2))->toBe('2 books');
+    expect($filter->pluralize('person', 4))->toBe('4 people');
+});
+
+test('pluralize handles irregular plurals correctly', function () {
+    $filter = new StringMarkup();
+
+    expect($filter->pluralize('child', 3))->toBe('3 children');
+    expect($filter->pluralize('sheep', 5))->toBe('5 sheep');
+});
+
+test('pluralize uses default count of 2 when not specified', function () {
+    $filter = new StringMarkup();
+
+    expect($filter->pluralize('book'))->toBe('2 books');
+    expect($filter->pluralize('person'))->toBe('2 people');
+});
+
+test('markdown_to_html converts basic markdown to HTML', function () {
+    $filter = new StringMarkup();
+    $markdown = 'This is *italic* and **bold**.';
+
+    // The exact HTML output might vary depending on the Parsedown implementation
+    // So we'll check for the presence of HTML tags rather than the exact output
+    $result = $filter->markdown_to_html($markdown);
+
+    expect($result)->toContain('<em>italic</em>');
+    expect($result)->toContain('<strong>bold</strong>');
+});
+
+test('markdown_to_html converts links correctly', function () {
+    $filter = new StringMarkup();
+    $markdown = 'This is [a link](https://example.com).';
+
+    $result = $filter->markdown_to_html($markdown);
+
+    expect($result)->toContain('<a href="https://example.com">a link</a>');
+});
+
+test('markdown_to_html handles fallback when Parsedown is not available', function () {
+    // Create a mock that simulates Parsedown not being available
+    $filter = new class extends StringMarkup
+    {
+        public function markdown_to_html(string $markdown): string
+        {
+            // Force the fallback path
+            return nl2br(htmlspecialchars($markdown));
+        }
+    };
+
+    $markdown = 'This is *italic* and [a link](https://example.com).';
+    $result = $filter->markdown_to_html($markdown);
+
+    expect($result)->toBe('This is *italic* and [a link](https://example.com).');
+});
+
+test('strip_html removes HTML tags', function () {
+    $filter = new StringMarkup();
+    $html = '<p>This is <strong>bold</strong> and <em>italic</em>.</p>';
+
+    expect($filter->strip_html($html))->toBe('This is bold and italic.');
+});
+
+test('strip_html preserves text content', function () {
+    $filter = new StringMarkup();
+    $html = '<div>Hello, <span>world</span>!</div>';
+
+    expect($filter->strip_html($html))->toBe('Hello, world!');
+});
+
+test('strip_html handles nested tags', function () {
+    $filter = new StringMarkup();
+    $html = '<div><p>Paragraph <strong>with <em>nested</em> tags</strong>.</p></div>';
+
+    expect($filter->strip_html($html))->toBe('Paragraph with nested tags.');
+});
diff --git a/tests/Unit/Liquid/Filters/UniquenessTest.php b/tests/Unit/Liquid/Filters/UniquenessTest.php
new file mode 100644
index 0000000..291f312
--- /dev/null
+++ b/tests/Unit/Liquid/Filters/UniquenessTest.php
@@ -0,0 +1,13 @@
+<?php
+
+use App\Liquid\Filters\Uniqueness;
+
+test('append_random appends a random string with 4 characters', function () {
+    $filter = new Uniqueness();
+    $result = $filter->append_random('chart-');
+
+    // Check that the result starts with the prefix
+    expect($result)->toStartWith('chart-');
+    // Check that the result is longer than just the prefix (has random part)
+    expect(mb_strlen($result))->toBe(mb_strlen('chart-') + 4);
+});