diff --git a/database/factories/H5PLibraryDependencyFactory.php b/database/factories/H5PLibraryDependencyFactory.php
new file mode 100644
index 00000000..786984f7
--- /dev/null
+++ b/database/factories/H5PLibraryDependencyFactory.php
@@ -0,0 +1,21 @@
+<?php
+
+namespace EscolaLms\HeadlessH5P\Database\Factories;
+
+use EscolaLms\HeadlessH5P\Models\H5PLibrary;
+use EscolaLms\HeadlessH5P\Models\H5PLibraryDependency;
+use Illuminate\Database\Eloquent\Factories\Factory;
+
+class H5PLibraryDependencyFactory extends Factory
+{
+    protected $model = H5PLibraryDependency::class;
+
+    public function definition()
+    {
+        return [
+            'library_id' => H5PLibrary::factory(),
+            'required_library_id' => H5PLibrary::factory(),
+            'dependency_type' => $this->faker->randomElement(['editor', 'preloaded'])
+        ];
+    }
+}
diff --git a/database/factories/H5PLibraryFactory.php b/database/factories/H5PLibraryFactory.php
index c858d479..0eb01515 100644
--- a/database/factories/H5PLibraryFactory.php
+++ b/database/factories/H5PLibraryFactory.php
@@ -27,6 +27,7 @@ public function definition()
             'semantics' => '',
             'tutorial_url' => '',
             'has_icon' => 0,
+            'add_to' => ''
         ];
     }
 }
diff --git a/database/migrations/2022_08_10_112954_add_add_to_column_to_hh5p_libraries_table.php b/database/migrations/2022_08_10_112954_add_add_to_column_to_hh5p_libraries_table.php
new file mode 100644
index 00000000..86716449
--- /dev/null
+++ b/database/migrations/2022_08_10_112954_add_add_to_column_to_hh5p_libraries_table.php
@@ -0,0 +1,22 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    public function up()
+    {
+        Schema::table('hh5p_libraries', function (Blueprint $table) {
+            $table->text('add_to')->nullable();
+        });
+    }
+
+    public function down()
+    {
+        Schema::table('hh5p_libraries', function (Blueprint $table) {
+            $table->dropColumn('add_to');
+        });
+    }
+};
diff --git a/src/Models/H5PLibrary.php b/src/Models/H5PLibrary.php
index a2be778c..8aba5a27 100644
--- a/src/Models/H5PLibrary.php
+++ b/src/Models/H5PLibrary.php
@@ -170,7 +170,8 @@ class H5PLibrary extends Model
         'hasIcon',
         'libraryId',
         'children',
-        'languages'
+        'languages',
+        'addTo'
     ];
 
     protected $appends = [
@@ -184,7 +185,8 @@ class H5PLibrary extends Model
         'dropLibraryCss',
         'tutorialUrl',
         'hasIcon',
-        'libraryId'
+        'libraryId',
+        'addTo'
     ];
 
     protected $hidden = [
@@ -196,6 +198,7 @@ class H5PLibrary extends Model
         'drop_library_css',
         'tutorial_url',
         'has_icon',
+        'add_to'
     ];
 
     public function getSemanticsAttribute($value)
@@ -248,6 +251,11 @@ public function getPreloadedCssAttribute():string
         return isset($this->attributes['preloaded_css']) ? $this->attributes['preloaded_css'] : '';
     }
 
+    public function getAddToAttribute():string
+    {
+        return isset($this->attributes['add_to']) ? $this->attributes['add_to'] : '';
+    }
+
     public function getDropLibraryCssAttribute():string
     {
         return isset($this->attributes['drop_library_css']) ? $this->attributes['drop_library_css'] : '';
@@ -265,7 +273,7 @@ public function getHasIconAttribute():string
 
     public function dependencies()
     {
-        return $this->hasMany(H5PLibraryDependency::class, 'library_id');
+        return $this->hasMany(H5PLibraryDependency::class, 'library_id', 'id');
     }
 
     public function children()
diff --git a/src/Models/H5PLibraryDependency.php b/src/Models/H5PLibraryDependency.php
index b48c4b90..cf1a6654 100644
--- a/src/Models/H5PLibraryDependency.php
+++ b/src/Models/H5PLibraryDependency.php
@@ -2,13 +2,17 @@
 
 namespace EscolaLms\HeadlessH5P\Models;
 
+use EscolaLms\HeadlessH5P\Database\Factories\H5PLibraryDependencyFactory;
+use Illuminate\Database\Eloquent\Factories\HasFactory;
 use Illuminate\Database\Eloquent\Model;
-use EscolaLms\HeadlessH5P\Models\H5PLibrary;
-use Illuminate\Database\Eloquent\Relations\BelongsTo;
+    use Illuminate\Database\Eloquent\Relations\BelongsTo;
 
 class H5PLibraryDependency extends Model
 {
+    use HasFactory;
+
     public $incrementing = false;
+
     public $timestamps = false;
 
     protected $table = 'hh5p_libraries_dependencies';
@@ -41,4 +45,9 @@ public function requiredLibrary():BelongsTo
     {
         return $this->belongsTo(H5PLibrary::class, 'required_library_id');
     }
+
+    protected static function newFactory(): H5PLibraryDependencyFactory
+    {
+        return H5PLibraryDependencyFactory::new();
+    }
 }
diff --git a/src/Repositories/H5PEditorStorageRepository.php b/src/Repositories/H5PEditorStorageRepository.php
index 1eaf29e0..dca795d9 100644
--- a/src/Repositories/H5PEditorStorageRepository.php
+++ b/src/Repositories/H5PEditorStorageRepository.php
@@ -26,18 +26,18 @@ class H5PEditorStorageRepository implements H5peditorStorage
      * @param string $lang Language code
      * @return string Translation in JSON format
      */
-    public function getLanguage($machineName, $majorVersion, $minorVersion, $language): string
+    public function getLanguage($machineName, $majorVersion, $minorVersion, $language): ?string
     {
         if (!isset($language)) {
-            return '';
+            return null;
         }
+
         $library = H5PLibrary::select(['id'])->where([
             ['major_version',  $majorVersion],
             ['minor_version', $minorVersion],
             ['name', $machineName],
         ])->first();
 
-
         if ($library) {
             $libraryLanguage = H5PLibraryLanguage::where([
                 ['library_id', $library->id],
@@ -50,7 +50,7 @@ public function getLanguage($machineName, $majorVersion, $minorVersion, $languag
             }
         }
 
-        return '';
+        return null;
     }
 
     /**
diff --git a/src/Repositories/H5PRepository.php b/src/Repositories/H5PRepository.php
index 62483d5c..10c40bd4 100644
--- a/src/Repositories/H5PRepository.php
+++ b/src/Repositories/H5PRepository.php
@@ -17,6 +17,7 @@
 use Illuminate\Support\Facades\DB;
 use DateTime;
 use Illuminate\Support\Facades\Cache;
+use Illuminate\Support\Facades\Storage;
 
 class H5PRepository implements H5PFrameworkInterface
 {
@@ -181,6 +182,8 @@ public function t($message, $replacements = []): string
      */
     public function getLibraryFileUrl($libraryFolderName, $fileName)
     {
+        $path = 'h5p/libraries/' . $libraryFolderName . '/' . $fileName;
+        return Storage::disk('local')->exists($path) ? Storage::disk('local')->url($path) : null;
     }
 
     /**
@@ -222,10 +225,25 @@ public function getUploadedH5pPath()
      *
      * @return array
      */
-    public function loadAddons()
+    public function loadAddons(): array
     {
-        // TODO this should return something
-        return [];
+        return H5PLibrary::query()
+            ->select(['l1.id', 'l1.name', 'l1.major_version', 'l1.minor_version', 'l1.patch_version', 'l1.preloaded_js', 'l1.preloaded_css', 'l1.add_to'])
+            ->from('hh5p_libraries as l1')
+            ->leftJoin('hh5p_libraries as l2', fn($join) => $join
+                ->on('l1.name', '=', 'l2.name')
+                ->on(fn($query) => $query
+                    ->on('l1.major_version', '<', 'l2.major_version')
+                    ->orOn(fn ($query) => $query
+                        ->orOn('l1.major_version', '=', 'l2.major_version')
+                        ->on('l1.minor_version', '<', 'l2.minor_version')
+                    )
+                )
+            )
+            ->whereNotNull('l1.add_to')
+            ->whereNull('l2.name')
+            ->get()
+            ->toArray();
     }
 
     /**
@@ -262,6 +280,7 @@ public function loadLibraries()
             ->orderBy('major_version', 'ASC')
             ->orderBy('minor_version', 'ASC')
             ->get();
+
         $libraries = [];
         foreach ($results as $library) {
             $libraries[$library->name][] = $library;
@@ -376,8 +395,6 @@ public function isInDevMode()
      */
     public function mayUpdateLibraries()
     {
-        // TODO check if current user is allowed to do this action
-        // best option use middleware on router
         return true;
     }
 
@@ -453,8 +470,9 @@ public function saveLibraryData(&$libraryData, $new = true)
             'preloaded_css' => $this->pathsToCsv($libraryData, 'preloadedCss'),
             'drop_library_css' => '', // TODO, what is this ?
             'semantics' => isset($libraryData['semantics']) ? $libraryData['semantics'] : '',
-            'tutorial_url' => isset($libraryData['tutorial_url']) ? isset($libraryData['tutorial_url']) : '',
+            'tutorial_url' => isset($libraryData['tutorial_url']) ?: '',
             'has_icon' => isset($libraryData['hasIcon']) ? 1 : 0,
+            'add_to' => isset($library['addTo']) ? json_encode($library['addTo']) : null
         ];
 
         $libObj = H5PLibrary::firstOrCreate($library);
@@ -496,7 +514,7 @@ public function saveLibraryData(&$libraryData, $new = true)
      */
     public function insertContent($content, $contentMainId = null)
     {
-        return $this->updateContent($content, $contentMainId = null);
+        return $this->updateContent($content, $contentMainId);
     }
 
     private function fixContentParamsMetadataLibraryTitle($content)
@@ -659,6 +677,7 @@ public function saveLibraryDependencies($libraryId, $dependencies, $dependency_t
      */
     public function copyLibraryUsage($contentId, $copyFromId, $contentMainId = null)
     {
+
     }
 
     /**
@@ -679,6 +698,7 @@ public function deleteContentData($contentId)
      */
     public function deleteLibraryUsage($contentId)
     {
+        H5PContent::findOrFail($contentId)->libraries()->delete();
     }
 
     /**
@@ -868,7 +888,7 @@ public function alterLibrarySemantics(&$semantics, $machineName, $majorVersion,
      */
     public function deleteLibraryDependencies($libraryId)
     {
-        // TODO this must be implemented
+        H5PLibrary::findOrFail($libraryId)->dependencies()->delete();
     }
 
     /**
@@ -1053,6 +1073,7 @@ public function setOption($name, $value)
      */
     public function updateContentFields($id, $fields)
     {
+        H5PContent::findOrFail($id)->update($fields);
     }
 
     /**
@@ -1064,6 +1085,7 @@ public function updateContentFields($id, $fields)
      */
     public function clearFilteredParameters($library_ids)
     {
+         H5PContent::query()->whereIn('library_id', $library_ids)->update(['filtered' => null]);
     }
 
     /**
@@ -1119,6 +1141,7 @@ public function getLibraryStats($type)
      */
     public function getNumAuthors()
     {
+        return H5PContent::query()->select(['user_id'])->distinct()->count('user_id');
     }
 
     /**
@@ -1220,16 +1243,8 @@ public function hasPermission($permission, $id = null)
      */
     public function replaceContentTypeCache($contentTypeCache)
     {
-
-        // TODO refactor this ugly code
-        // Replace existing content type cache
-        DB::table('hh5p_libraries_hub_cache')->truncate();
-
-        // TODO wrap this in a transaction
-
         foreach ($contentTypeCache->contentTypes as $ct) {
-            // Insert into db
-            H5pLibrariesHubCache::create([
+           $data[] = [
                 'machine_name' => $ct->id,
                 'major_version' => $ct->version->major,
                 'minor_version' => $ct->version->minor,
@@ -1245,14 +1260,19 @@ public function replaceContentTypeCache($contentTypeCache)
                 'is_recommended' => $ct->isRecommended === true ? 1 : 0,
                 'popularity' => $ct->popularity,
                 'screenshots' => json_encode($ct->screenshots),
-                'license' => json_encode(isset($ct->license) ? $ct->license : []),
+                'license' => json_encode($ct->license ?? []),
                 'example' => $ct->example,
-                'tutorial' => isset($ct->tutorial) ? $ct->tutorial : '',
-                'keywords' => json_encode(isset($ct->keywords) ? $ct->keywords : []),
-                'categories' => json_encode(isset($ct->categories) ? $ct->categories : []),
+                'tutorial' => $ct->tutorial ?? '',
+                'keywords' => json_encode($ct->keywords ?? []),
+                'categories' => json_encode($ct->categories ?? []),
                 'owner' => $ct->owner,
-            ]);
+            ];
         }
+
+        DB::transaction(function () use($data) {
+            H5pLibrariesHubCache::query()->delete();
+            H5pLibrariesHubCache::insert($data);
+        });
     }
 
     /**
diff --git a/tests/Fixture/H5PContentTypeFixture.php b/tests/Fixture/H5PContentTypeFixture.php
new file mode 100644
index 00000000..6a820649
--- /dev/null
+++ b/tests/Fixture/H5PContentTypeFixture.php
@@ -0,0 +1,85 @@
+<?php
+
+namespace EscolaLms\HeadlessH5P\Tests\Fixture;
+
+use Carbon\Carbon;
+use DateTime;
+use Faker\Factory as FakerFactory;
+use stdClass;
+
+class H5PContentTypeFixture
+{
+    private stdClass $data;
+
+    private int $count = 1;
+
+    public function __construct()
+    {
+        $this->data = new stdClass();
+    }
+
+    public static function fixture(): H5PContentTypeFixture
+    {
+        return new H5PContentTypeFixture();
+    }
+
+    public function count(int $count = 1): self
+    {
+        $this->count = $count;
+
+        return $this;
+    }
+
+    public function make(): self
+    {
+        if ($this->count <= 1) {
+            $this->data->contentTypes = $this->factory();
+
+            return $this;
+        }
+
+        for ($i = 0; $i < $this->count; $i++)
+        {
+            $this->data->contentTypes[] = $this->factory();
+        }
+
+        return $this;
+    }
+
+    public function get(): stdClass
+    {
+        return $this->data;
+    }
+
+    private function factory(): stdClass
+    {
+        $faker = FakerFactory::create();
+
+        $data = new stdClass();
+        $data->id = $faker->word;
+        $data->version = new stdClass();
+        $data->version->major = $faker->numberBetween(1, 10);
+        $data->version->minor = $faker->numberBetween(1, 10);
+        $data->version->patch = $faker->numberBetween(1, 10);
+        $data->coreApiVersionNeeded = new stdClass();
+        $data->coreApiVersionNeeded->major = $faker->numberBetween(1, 10);
+        $data->coreApiVersionNeeded->minor = $faker->numberBetween(1, 10);
+        $data->title = $faker->word;
+        $data->summary = $faker->words(3, true);
+        $data->description = $faker->words(3, true);
+        $data->icon = $faker->url;
+        $data->createdAt = Carbon::now()->toISOString();
+        $data->updatedAt =  Carbon::now()->toISOString();
+        $data->isRecommended = $faker->boolean;
+        $data->popularity = $faker->numberBetween(1, 10);
+        $data->screenshots = $faker->url;
+        $data->license = array();
+        $data->example = $faker->word;
+        $data->tutorial = $faker->url;
+        $data->keywords = array($faker->word);
+        $data->categories = array($faker->word);
+        $data->owner = $faker->firstName . ' ' . $faker->lastName;
+
+        return $data;
+    }
+}
diff --git a/tests/Repositories/H5PRepositoryTest.php b/tests/Repositories/H5PRepositoryTest.php
index 59d5ef40..eea3f8a5 100644
--- a/tests/Repositories/H5PRepositoryTest.php
+++ b/tests/Repositories/H5PRepositoryTest.php
@@ -2,10 +2,16 @@
 
 namespace EscolaLms\HeadlessH5P\Tests\Repositories;
 
+use EscolaLms\HeadlessH5P\Models\H5PContent;
+use EscolaLms\HeadlessH5P\Models\H5PContentLibrary;
+use EscolaLms\HeadlessH5P\Models\H5PLibrary;
+use EscolaLms\HeadlessH5P\Models\H5PLibraryDependency;
 use EscolaLms\HeadlessH5P\Repositories\H5PRepository;
+use EscolaLms\HeadlessH5P\Tests\Fixture\H5PContentTypeFixture;
 use EscolaLms\HeadlessH5P\Tests\TestCase;
 use GuzzleHttp\Psr7\Response;
 use H5PHubEndpoints;
+use Illuminate\Database\Eloquent\ModelNotFoundException;
 use Illuminate\Foundation\Testing\DatabaseTransactions;
 
 class H5PRepositoryTest extends TestCase
@@ -73,4 +79,145 @@ public function testFetchExternalDataShouldReturnFalseWhenStatusIsDifferentFrom2
 
         $this->assertFalse($result);
     }
+
+    public function testLoadAddonsShouldReturnHigherVersionLibrary(): void
+    {
+        H5PLibrary::factory()->create(['name' => 'Test', 'major_version' => 1, 'minor_version' => 2, 'add_to' => 'sth']);
+        $library1 = H5PLibrary::factory()->create(['name' => 'Test', 'major_version' => 1, 'minor_version' => 3, 'add_to' => 'sth']);
+
+        $result = $this->repository->loadAddons();
+
+        $this->assertCount(1, $result);
+        $this->assertEquals($library1->getKey(), $result[0]['id']);
+        $this->assertEquals(3, $result[0]['minorVersion']);
+        $this->assertEquals(1, $result[0]['majorVersion']);
+    }
+
+    public function testLoadAddonsShouldReturnHigherMajorVersionLibrary(): void
+    {
+        $library1 = H5PLibrary::factory()->create(['name' => 'Test', 'major_version' => 2, 'minor_version' => 1, 'add_to' => 'sth']);
+        H5PLibrary::factory()->create(['name' => 'Test', 'major_version' => 1, 'minor_version' => 1, 'add_to' => 'sth']);
+
+        $result = $this->repository->loadAddons();
+
+        $this->assertCount(1, $result);
+        $this->assertEquals($library1->getKey(), $result[0]['id']);
+        $this->assertEquals(1, $result[0]['minorVersion']);
+        $this->assertEquals(2, $result[0]['majorVersion']);
+    }
+
+    public function testLoadAddonsShouldReturnAllLibrariesWhenNamesIsNotSame(): void
+    {
+        H5PLibrary::factory()->create(['name' => 'Test1', 'major_version' => 2, 'minor_version' => 1, 'add_to' => 'sth']);
+        H5PLibrary::factory()->create(['name' => 'Test2', 'major_version' => 1, 'minor_version' => 3, 'add_to' => 'sth']);
+
+        $result = $this->repository->loadAddons();
+
+        $this->assertCount(2, $result);
+    }
+
+    public function testDeleteLibraryUsageShouldDeleteLibrariesById(): void
+    {
+        $h5pContent = H5PContent::factory()
+            ->has(H5PContentLibrary::factory()->count(5), 'libraries')
+            ->create(['library_id' => H5PLibrary::factory()->create()->getKey()]);
+
+        $this->assertCount(5, $h5pContent->libraries);
+
+        $this->repository->deleteLibraryUsage($h5pContent->getKey());
+
+        $this->assertCount(0, H5PContent::find($h5pContent->getKey())->libraries);
+    }
+
+    public function testDeleteLibraryUsageShouldFailWhenContentNotExists(): void
+    {
+        $this->expectException(ModelNotFoundException::class);
+        $this->repository->deleteLibraryUsage(1);
+    }
+
+    public function testDeleteLibraryDependenciesShouldDeleteAllDependencies(): void
+    {
+        $library = H5PLibrary::factory()
+            ->has(H5PLibraryDependency::factory(), 'dependencies')
+            ->create();
+
+        $this->assertCount(1, $library->dependencies);
+
+        $this->repository->deleteLibraryDependencies($library->getKey());
+
+        $this->assertCount(0, H5PLibrary::find($library->getKey())->dependencies);
+    }
+
+    public function testDeleteLibraryDependenciesShouldFailWhenLibraryNotExists(): void
+    {
+        $this->expectException(ModelNotFoundException::class);
+        $this->repository->deleteLibraryDependencies(123);
+    }
+
+    public function testUpdateContentFieldsShouldUpdateSlugAndFilteredFields(): void
+    {
+        $h5pContent = H5PContent::factory()->create(['library_id' => H5PLibrary::factory()->create()->getKey()]);
+
+        $this->repository->updateContentFields($h5pContent->getKey(), ['slug' => 'slug-123', 'filtered' => '{"test": "test"}']);
+
+        $result = H5PContent::find($h5pContent->getKey());
+        $this->assertEquals('slug-123', $result->slug);
+        $this->assertEquals('{"test": "test"}', $result->filtered);
+        $this->assertNotEquals($h5pContent->slug, $result->slug);
+        $this->assertNotEquals($h5pContent->filtered, $result->filtered);
+    }
+
+    public function testClearFilteredParametersShouldClearFilteredField(): void
+    {
+        $libraryId1 = H5PLibrary::factory()->create()->getKey();
+        $libraryId2 = H5PLibrary::factory()->create()->getKey();
+        $h5pContent1 = H5PContent::factory()->create(['library_id' => $libraryId1, 'filtered' => '{"foo": "bar"']);
+        $h5pContent2 = H5PContent::factory()->create(['library_id' => $libraryId1, 'filtered' => '{"foo": "bar"']);
+        $h5pContent3 = H5PContent::factory()->create(['library_id' => $libraryId2, 'filtered' => '{"foo": "bar"']);
+
+        $this->assertNotNull($h5pContent1->filtered);
+        $this->assertNotNull($h5pContent2->filtered);
+        $this->assertNotNull($h5pContent3->filtered);
+
+        $this->repository->clearFilteredParameters([$libraryId1]);
+
+        $this->assertNull(H5PContent::find($h5pContent1->getKey())->filtered);
+        $this->assertNull(H5PContent::find($h5pContent2->getKey())->filtered);
+        $this->assertNotNull(H5PContent::find($h5pContent3->getKey())->filtered);
+    }
+
+
+    public function testGetNumAuthors(): void
+    {
+        H5PContent::factory()->create(['library_id' => 1, 'user_id' => 1]);
+        H5PContent::factory()->create(['library_id' => 1, 'user_id' => 12]);
+
+        $result = $this->repository->getNumAuthors();
+
+        $this->assertEquals(2, $result);
+    }
+
+    public function testReplaceContentTypeCacheShouldCreateContentType(): void
+    {
+        $data = H5PContentTypeFixture::fixture()->count(3)->make()->get();
+
+        $this->assertDatabaseCount('hh5p_libraries_hub_cache', 0);
+
+        $this->repository->replaceContentTypeCache($data);
+
+        $this->assertDatabaseCount('hh5p_libraries_hub_cache', 3);
+    }
+
+    public function testReplaceContentTypeCacheShouldTruncateExistingDataAndCreateContentType(): void
+    {
+        $data = H5PContentTypeFixture::fixture()->count(3)->make()->get();
+        $this->repository->replaceContentTypeCache($data);
+
+        $this->assertDatabaseCount('hh5p_libraries_hub_cache', 3);
+
+        $data = H5PContentTypeFixture::fixture()->count(10)->make()->get();
+        $this->repository->replaceContentTypeCache($data);
+
+        $this->assertDatabaseCount('hh5p_libraries_hub_cache', 10);
+    }
 }