diff --git a/.gitignore b/.gitignore
index 8affbb6..d027d61 100644
--- a/.gitignore
+++ b/.gitignore
@@ -156,6 +156,7 @@ vendor/
 composer.lock
 *.phar
 codeception.phar
+.phpunit.cache/
 .phpunit.result.cache
 .php_cs.cache
 .php-cs-fixer.cache
diff --git a/composer.json b/composer.json
index c21717f..a5fd414 100644
--- a/composer.json
+++ b/composer.json
@@ -15,9 +15,23 @@
         "php": ">=8.1"
     },
     "require-dev": {
-        "squizlabs/php_codesniffer": "^3.7",
+        "joomla/coding-standards": "^3.0",
         "phpstan/phpstan": "^1.10",
-        "joomla/coding-standards": "^3.0"
+        "phpunit/phpunit": "^10.5",
+        "squizlabs/php_codesniffer": "^3.7"
+    },
+    "autoload": {
+        "psr-4": {
+            "Joomla\\Plugin\\System\\MokoOG\\": "source/packages/plg_system_mokoog/src/",
+            "Joomla\\Plugin\\Content\\MokoOG\\": "source/packages/plg_content_mokoog/src/",
+            "Joomla\\Plugin\\WebServices\\MokoOG\\": "source/packages/plg_webservices_mokoog/src/",
+            "Joomla\\Component\\MokoOG\\Administrator\\": "source/packages/com_mokoog/src/"
+        }
+    },
+    "autoload-dev": {
+        "psr-4": {
+            "Mokoconsulting\\MokoOG\\Tests\\": "tests/"
+        }
     },
     "minimum-stability": "alpha",
     "prefer-stable": true,
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
new file mode 100644
index 0000000..9f4fb2a
--- /dev/null
+++ b/phpunit.xml.dist
@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/10.5/phpunit.xsd"
+         bootstrap="tests/bootstrap.php"
+         colors="true"
+         cacheDirectory=".phpunit.cache">
+    <testsuites>
+        <testsuite name="Unit">
+            <directory>tests/Unit</directory>
+        </testsuite>
+    </testsuites>
+    <source>
+        <include>
+            <directory>source/packages</directory>
+        </include>
+    </source>
+</phpunit>
diff --git a/tests/Unit/Helper/JsonLdBuilderTest.php b/tests/Unit/Helper/JsonLdBuilderTest.php
new file mode 100644
index 0000000..e7b3921
--- /dev/null
+++ b/tests/Unit/Helper/JsonLdBuilderTest.php
@@ -0,0 +1,257 @@
+<?php
+
+/**
+ * @package     MokoSuiteOpenGraph
+ * @subpackage  Tests
+ * @author      Moko Consulting <hello@mokoconsulting.tech>
+ * @copyright   Copyright (C) 2026 Moko Consulting. All rights reserved.
+ * @license     GNU General Public License version 3 or later; see LICENSE
+ */
+
+namespace Mokoconsulting\MokoOG\Tests\Unit\Helper;
+
+use Joomla\Plugin\System\MokoOG\Helper\JsonLdBuilder;
+use PHPUnit\Framework\TestCase;
+
+class JsonLdBuilderTest extends TestCase
+{
+    // ── FAQPage ──────────────────────────────────────────────────────
+
+    public function testBuildFaqReturnsNullForEmptyArray(): void
+    {
+        $this->assertNull(JsonLdBuilder::buildFaq([]));
+    }
+
+    public function testBuildFaqSkipsEmptyQuestions(): void
+    {
+        $faqs = [
+            ['question' => '', 'answer' => 'An answer'],
+            ['question' => 'Valid?', 'answer' => ''],
+            ['question' => '  ', 'answer' => 'Still empty'],
+        ];
+
+        $this->assertNull(JsonLdBuilder::buildFaq($faqs));
+    }
+
+    public function testBuildFaqReturnsValidSchema(): void
+    {
+        $faqs = [
+            ['question' => 'What is OG?', 'answer' => 'Open Graph protocol.'],
+            ['question' => 'Why use it?', 'answer' => 'Better social previews.'],
+        ];
+
+        $result = JsonLdBuilder::buildFaq($faqs);
+
+        $this->assertNotNull($result);
+        $this->assertSame('https://schema.org', $result['@context']);
+        $this->assertSame('FAQPage', $result['@type']);
+        $this->assertCount(2, $result['mainEntity']);
+        $this->assertSame('Question', $result['mainEntity'][0]['@type']);
+        $this->assertSame('What is OG?', $result['mainEntity'][0]['name']);
+        $this->assertSame('Open Graph protocol.', $result['mainEntity'][0]['acceptedAnswer']['text']);
+    }
+
+    // ── HowTo ────────────────────────────────────────────────────────
+
+    public function testBuildHowToReturnsNullForEmptySteps(): void
+    {
+        $this->assertNull(JsonLdBuilder::buildHowTo('Test', []));
+        $this->assertNull(JsonLdBuilder::buildHowTo('Test', ['', '  ']));
+    }
+
+    public function testBuildHowToReturnsValidSchema(): void
+    {
+        $result = JsonLdBuilder::buildHowTo('Install Joomla', ['Download ZIP', 'Upload files', 'Run installer']);
+
+        $this->assertNotNull($result);
+        $this->assertSame('HowTo', $result['@type']);
+        $this->assertSame('Install Joomla', $result['name']);
+        $this->assertCount(3, $result['step']);
+        $this->assertSame(1, $result['step'][0]['position']);
+        $this->assertSame('HowToStep', $result['step'][0]['@type']);
+        $this->assertSame('Download ZIP', $result['step'][0]['text']);
+        $this->assertArrayNotHasKey('image', $result);
+    }
+
+    public function testBuildHowToIncludesImageWhenProvided(): void
+    {
+        $result = JsonLdBuilder::buildHowTo('Fix a bike', ['Remove wheel'], 'https://example.com/bike.jpg');
+
+        $this->assertNotNull($result);
+        $this->assertSame('https://example.com/bike.jpg', $result['image']);
+    }
+
+    // ── Recipe ───────────────────────────────────────────────────────
+
+    public function testBuildRecipeReturnsNullWhenNoData(): void
+    {
+        $data = (object) ['name' => '', 'description' => ''];
+
+        $this->assertNull(JsonLdBuilder::buildRecipe($data));
+    }
+
+    public function testBuildRecipeCalculatesTotalTime(): void
+    {
+        $data = (object) [
+            'name'     => 'Pasta',
+            'prepTime' => 'PT15M',
+            'cookTime' => 'PT30M',
+        ];
+
+        $result = JsonLdBuilder::buildRecipe($data);
+
+        $this->assertNotNull($result);
+        $this->assertSame('Recipe', $result['@type']);
+        $this->assertSame('PT45M', $result['totalTime']);
+    }
+
+    public function testBuildRecipeSplitsIngredientsByNewline(): void
+    {
+        $data = (object) [
+            'name'        => 'Salad',
+            'ingredients' => "Lettuce\nTomato\nOnion",
+        ];
+
+        $result = JsonLdBuilder::buildRecipe($data);
+
+        $this->assertNotNull($result);
+        $this->assertSame(['Lettuce', 'Tomato', 'Onion'], $result['recipeIngredient']);
+    }
+
+    // ── Event ────────────────────────────────────────────────────────
+
+    public function testBuildEventReturnsNullWithoutStartDate(): void
+    {
+        $data = (object) ['name' => 'Conference', 'startDate' => ''];
+
+        $this->assertNull(JsonLdBuilder::buildEvent($data));
+    }
+
+    public function testBuildEventIncludesLocationAndOffers(): void
+    {
+        $data = (object) [
+            'name'      => 'Tech Summit',
+            'startDate' => '2026-09-01T09:00:00',
+            'endDate'   => '2026-09-01T17:00:00',
+            'location'  => (object) [
+                'name'    => 'Convention Center',
+                'address' => '123 Main St',
+            ],
+            'offers' => (object) [
+                'price'    => '99.00',
+                'currency' => 'EUR',
+                'url'      => 'https://example.com/tickets',
+            ],
+        ];
+
+        $result = JsonLdBuilder::buildEvent($data);
+
+        $this->assertNotNull($result);
+        $this->assertSame('Event', $result['@type']);
+        $this->assertSame('2026-09-01T09:00:00', $result['startDate']);
+        $this->assertSame('2026-09-01T17:00:00', $result['endDate']);
+        $this->assertSame('Place', $result['location']['@type']);
+        $this->assertSame('Convention Center', $result['location']['name']);
+        $this->assertSame('Offer', $result['offers']['@type']);
+        $this->assertSame('99.00', $result['offers']['price']);
+        $this->assertSame('EUR', $result['offers']['priceCurrency']);
+    }
+
+    // ── LocalBusiness ────────────────────────────────────────────────
+
+    public function testBuildLocalBusinessReturnsNullWithoutName(): void
+    {
+        $params = $this->createParamsMock([]);
+
+        $this->assertNull(JsonLdBuilder::buildLocalBusiness($params));
+    }
+
+    public function testBuildLocalBusinessIncludesAddress(): void
+    {
+        $params = $this->createParamsMock([
+            'business_name'  => 'Moko Consulting',
+            'street_address' => '456 Oak Ave',
+            'city'           => 'Austin',
+            'region'         => 'TX',
+            'postal_code'    => '78701',
+            'country'        => 'US',
+            'telephone'      => '+1-555-0100',
+        ]);
+
+        $result = JsonLdBuilder::buildLocalBusiness($params);
+
+        $this->assertNotNull($result);
+        $this->assertSame('LocalBusiness', $result['@type']);
+        $this->assertSame('Moko Consulting', $result['name']);
+        $this->assertSame('PostalAddress', $result['address']['@type']);
+        $this->assertSame('456 Oak Ave', $result['address']['streetAddress']);
+        $this->assertSame('Austin', $result['address']['addressLocality']);
+        $this->assertSame('TX', $result['address']['addressRegion']);
+        $this->assertSame('78701', $result['address']['postalCode']);
+        $this->assertSame('US', $result['address']['addressCountry']);
+        $this->assertSame('+1-555-0100', $result['telephone']);
+    }
+
+    // ── VideoObject ──────────────────────────────────────────────────
+
+    public function testBuildVideoReturnsNullForEmptyUrl(): void
+    {
+        $this->assertNull(JsonLdBuilder::buildVideo(''));
+    }
+
+    public function testBuildVideoAddsEmbedUrlForYoutube(): void
+    {
+        $result = JsonLdBuilder::buildVideo(
+            'https://www.youtube.com/watch?v=dQw4w9WgXcQ',
+            'Test Video',
+            'A description'
+        );
+
+        $this->assertNotNull($result);
+        $this->assertSame('VideoObject', $result['@type']);
+        $this->assertSame('https://www.youtube.com/watch?v=dQw4w9WgXcQ', $result['contentUrl']);
+        $this->assertSame('https://www.youtube.com/embed/dQw4w9WgXcQ', $result['embedUrl']);
+        $this->assertSame('Test Video', $result['name']);
+    }
+
+    // ── toScriptTag ──────────────────────────────────────────────────
+
+    public function testToScriptTagEscapesClosingScriptTags(): void
+    {
+        $schema = [
+            '@context' => 'https://schema.org',
+            '@type'    => 'Article',
+            'headline' => 'Test </script><script>alert(1)</script>',
+        ];
+
+        $output = JsonLdBuilder::toScriptTag($schema);
+
+        $this->assertStringStartsWith('<script type="application/ld+json">', $output);
+        $this->assertStringEndsWith('</script>', $output);
+        // The closing </script> inside the JSON must be escaped
+        $this->assertStringNotContainsString('</script><script>', $output);
+        $this->assertStringContainsString('<\\/script>', $output);
+    }
+
+    // ── Helper ───────────────────────────────────────────────────────
+
+    /**
+     * Create a mock object that mimics Joomla's Registry->get($key, $default).
+     */
+    private function createParamsMock(array $values): object
+    {
+        return new class ($values) {
+            private array $data;
+
+            public function __construct(array $data)
+            {
+                $this->data = $data;
+            }
+
+            public function get(string $key, mixed $default = ''): mixed
+            {
+                return $this->data[$key] ?? $default;
+            }
+        };
+    }
+}
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
new file mode 100644
index 0000000..36f2c94
--- /dev/null
+++ b/tests/bootstrap.php
@@ -0,0 +1,13 @@
+<?php
+
+/**
+ * @package     MokoSuiteOpenGraph
+ * @subpackage  Tests
+ * @author      Moko Consulting <hello@mokoconsulting.tech>
+ * @copyright   Copyright (C) 2026 Moko Consulting. All rights reserved.
+ * @license     GNU General Public License version 3 or later; see LICENSE
+ */
+
+define('_JEXEC', 1);
+
+require_once __DIR__ . '/../vendor/autoload.php';