diff --git a/jsonld.api.php b/jsonld.api.php
new file mode 100644
index 0000000..7066ac1
--- /dev/null
+++ b/jsonld.api.php
@@ -0,0 +1,32 @@
+<?php
+
+/**
+ * @file
+ * Hooks and stuff.
+ */
+
+use Drupal\Core\Entity\EntityInterface;
+
+/**
+ * Hook to alter the jsonld normalized array before it is encoded to json.
+ *
+ * @param \Drupal\Core\Entity\EntityInterface $entity
+ *   The entity we are normalizing.
+ * @param array $normalized
+ *   The current normalized array.
+ * @param array $context
+ *   The context for the normalization.
+ */
+function hook_jsonld_alter_normalized_array(EntityInterface $entity, array &$normalized, array $context) {
+  if ($entity->getEntityTypeId() == 'node') {
+    if (isset($normalized['@graph'])) {
+      if (!is_array($normalized["@graph"])) {
+        $normalized['@graph'] = [$normalized['@graph']];
+      }
+      $normalized['@graph'][] = [
+        '@id' => 'http://example.org/first/name',
+        '@type' => 'schemaOrg:Person',
+      ];
+    }
+  }
+}
diff --git a/jsonld.services.yml b/jsonld.services.yml
index fb07de3..0cfaf15 100644
--- a/jsonld.services.yml
+++ b/jsonld.services.yml
@@ -17,10 +17,10 @@ services:
     class: Drupal\jsonld\Normalizer\FileEntityNormalizer
     tags:
       - { name: normalizer, priority: 20 }
-    arguments: ['@entity.manager', '@http_client', '@hal.link_manager', '@module_handler']
+    arguments: ['@entity_type.manager', '@http_client', '@hal.link_manager', '@module_handler', '@file_system']
   serializer.normalizer.entity.jsonld:
     class: Drupal\jsonld\Normalizer\ContentEntityNormalizer
-    arguments: ['@hal.link_manager', '@entity.manager', '@module_handler']
+    arguments: ['@hal.link_manager', '@entity_type.manager', '@module_handler']
     tags:
       - { name: normalizer, priority: 10 }
   serializer.encoder.jsonld:
diff --git a/src/Normalizer/ContentEntityNormalizer.php b/src/Normalizer/ContentEntityNormalizer.php
index 4b59567..99315f9 100644
--- a/src/Normalizer/ContentEntityNormalizer.php
+++ b/src/Normalizer/ContentEntityNormalizer.php
@@ -3,7 +3,7 @@
 namespace Drupal\jsonld\Normalizer;
 
 use Drupal\Core\Entity\EntityInterface;
-use Drupal\Core\Entity\EntityManagerInterface;
+use Drupal\Core\Entity\EntityTypeManagerInterface;
 use Drupal\Core\Extension\ModuleHandlerInterface;
 use Drupal\hal\LinkManager\LinkManagerInterface;
 use Symfony\Component\Serializer\Exception\UnexpectedValueException;
@@ -13,6 +13,8 @@
  */
 class ContentEntityNormalizer extends NormalizerBase {
 
+  const NORMALIZE_ALTER_HOOK = "jsonld_alter_normalized_array";
+
   /**
    * The interface or class that this Normalizer supports.
    *
@@ -46,12 +48,12 @@ class ContentEntityNormalizer extends NormalizerBase {
    *
    * @param \Drupal\hal\LinkManager\LinkManagerInterface $link_manager
    *   The hypermedia link manager.
-   * @param \Drupal\Core\Entity\EntityManagerInterface $entity_manager
+   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_manager
    *   The entity manager.
    * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
    *   The module handler.
    */
-  public function __construct(LinkManagerInterface $link_manager, EntityManagerInterface $entity_manager, ModuleHandlerInterface $module_handler) {
+  public function __construct(LinkManagerInterface $link_manager, EntityTypeManagerInterface $entity_manager, ModuleHandlerInterface $module_handler) {
 
     $this->linkManager = $link_manager;
     $this->entityManager = $entity_manager;
@@ -67,12 +69,17 @@ public function normalize($entity, $format = NULL, array $context = []) {
     // @TODO check $format before going RDF crazy
     $normalized = [];
 
+    if (isset($context['depth'])) {
+      $context['depth'] += 1;
+    }
+
     $context += [
       'account' => NULL,
       'included_fields' => NULL,
       'needs_jsonldcontext' => FALSE,
       'embedded' => FALSE,
       'namespaces' => rdf_get_namespaces(),
+      'depth' => 0,
     ];
 
     if ($context['needs_jsonldcontext']) {
@@ -95,7 +102,7 @@ public function normalize($entity, $format = NULL, array $context = []) {
     // not shortened ones. So we replace them in place.
     if ($context['needs_jsonldcontext'] === FALSE && is_array($types)) {
       for ($i = 0; $i < count($types); $i++) {
-        $types[$i] = $this->escapePrefix($types[$i], $context['namespaces']);
+        $types[$i] = ContentEntityNormalizer::escapePrefix($types[$i], $context['namespaces']);
       }
     }
 
@@ -126,6 +133,7 @@ public function normalize($entity, $format = NULL, array $context = []) {
 
     $context['current_entity_id'] = $this->getEntityUri($entity);
     $context['current_entity_rdf_mapping'] = $rdf_mappings;
+
     foreach ($fields as $name => $field) {
       // Just process fields that have rdf mappings defined.
       // We could also pass as not contextualized keys the others
@@ -150,6 +158,12 @@ public function normalize($entity, $format = NULL, array $context = []) {
     if (!$context['embedded']) {
       $normalized['@graph'] = array_values($normalized['@graph']);
     }
+
+    if (isset($context['depth']) && $context['depth'] == 0) {
+      $this->moduleHandler->invokeAll(self::NORMALIZE_ALTER_HOOK,
+        [$entity, &$normalized, $context]
+      );
+    }
     return $normalized;
   }
 
@@ -238,9 +252,9 @@ protected function getEntityUri(EntityInterface $entity) {
     // Some entity types don't provide a canonical link template, at least call
     // out to ->url().
     if ($entity->isNew() || !$entity->hasLinkTemplate('canonical')) {
-      return $entity->url('canonical', []);
+      return $entity->toUrl('canonical', []);
     }
-    $url = $entity->urlInfo('canonical', ['absolute' => TRUE]);
+    $url = $entity->toUrl('canonical', ['absolute' => TRUE]);
     return $url->setRouteParameter('_format', 'jsonld')->toString();
   }
 
diff --git a/src/Normalizer/FileEntityNormalizer.php b/src/Normalizer/FileEntityNormalizer.php
index 6a3e9a8..0fe5198 100644
--- a/src/Normalizer/FileEntityNormalizer.php
+++ b/src/Normalizer/FileEntityNormalizer.php
@@ -2,8 +2,9 @@
 
 namespace Drupal\jsonld\Normalizer;
 
-use Drupal\Core\Entity\EntityManagerInterface;
+use Drupal\Core\Entity\EntityTypeManagerInterface;
 use Drupal\Core\Extension\ModuleHandlerInterface;
+use Drupal\Core\File\FileSystemInterface;
 use Drupal\hal\LinkManager\LinkManagerInterface;
 use GuzzleHttp\ClientInterface;
 
@@ -26,10 +27,17 @@ class FileEntityNormalizer extends ContentEntityNormalizer {
    */
   protected $httpClient;
 
+  /**
+   * The Drupal file system.
+   *
+   * @var \Drupal\Core\File\FileSystemInterface
+   */
+  protected $fileSystem;
+
   /**
    * Constructs a FileEntityNormalizer object.
    *
-   * @param \Drupal\Core\Entity\EntityManagerInterface $entity_manager
+   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_manager
    *   The entity manager.
    * @param \GuzzleHttp\ClientInterface $http_client
    *   The HTTP Client.
@@ -37,12 +45,19 @@ class FileEntityNormalizer extends ContentEntityNormalizer {
    *   The hypermedia link manager.
    * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
    *   The module handler.
+   * @param \Drupal\Core\File\FileSystemInterface $file_system
+   *   The file system handler.
    */
-  public function __construct(EntityManagerInterface $entity_manager, ClientInterface $http_client, LinkManagerInterface $link_manager, ModuleHandlerInterface $module_handler) {
+  public function __construct(EntityTypeManagerInterface $entity_manager,
+                              ClientInterface $http_client,
+                              LinkManagerInterface $link_manager,
+                              ModuleHandlerInterface $module_handler,
+                              FileSystemInterface $file_system) {
 
     parent::__construct($link_manager, $entity_manager, $module_handler);
 
     $this->httpClient = $http_client;
+    $this->fileSystem = $file_system;
   }
 
   /**
@@ -64,7 +79,7 @@ public function denormalize($data, $class, $format = NULL, array $context = [])
 
     $file_data = (string) $this->httpClient->get($data['uri'][0]['value'])->getBody();
 
-    $path = 'temporary://' . drupal_basename($data['uri'][0]['value']);
+    $path = 'temporary://' . $this->fileSystem->basename($data['uri'][0]['value']);
     $data['uri'] = file_unmanaged_save_data($file_data, $path);
 
     return $this->entityManager->getStorage('file')->create($data);
diff --git a/src/Normalizer/NormalizerBase.php b/src/Normalizer/NormalizerBase.php
index a3e1468..cb66c76 100644
--- a/src/Normalizer/NormalizerBase.php
+++ b/src/Normalizer/NormalizerBase.php
@@ -55,7 +55,7 @@ public function supportsDenormalization($data, $type, $format = NULL) {
    * @return string
    *   The predicate with escaped namespace prefix.
    */
-  protected function escapePrefix($predicate, array $namespaces) {
+  public static function escapePrefix($predicate, array $namespaces) {
 
     $exploded = explode(":", $predicate);
     if (!isset($namespaces[$exploded[0]])) {
diff --git a/tests/json_alter_normalize_hooks.info.yml b/tests/json_alter_normalize_hooks.info.yml
new file mode 100644
index 0000000..105d1c9
--- /dev/null
+++ b/tests/json_alter_normalize_hooks.info.yml
@@ -0,0 +1,6 @@
+name: 'Jsonld hook tests'
+type: module
+package: Testing
+core: 8.x
+dependencies:
+  - jsonld
diff --git a/tests/json_alter_normalize_hooks.module b/tests/json_alter_normalize_hooks.module
new file mode 100644
index 0000000..8509a70
--- /dev/null
+++ b/tests/json_alter_normalize_hooks.module
@@ -0,0 +1,25 @@
+<?php
+
+/**
+ * @file
+ * A test module to implement the hooks to be tested.
+ */
+
+use Drupal\Core\Entity\EntityInterface;
+
+/**
+ * Implements hook_jsonld_alter_normalized_array().
+ */
+function json_alter_normalize_hooks_jsonld_alter_normalized_array(EntityInterface $entity, array &$normalized, array $context) {
+  if (isset($normalized['@graph'])) {
+    if (!is_array($normalized['@graph'])) {
+      $normalized['@graph'] = [
+        [$normalized['@graph']],
+      ];
+    }
+    $normalized['@graph'][] = [
+      '@id' => 'json_alter_normalize_hooks',
+      'http://purl.org/dc/elements/1.1/title' => 'The hook is tested.',
+    ];
+  }
+}
diff --git a/tests/src/Kernel/JsonldContextGeneratorTest.php b/tests/src/Kernel/JsonldContextGeneratorTest.php
index 881584b..bc0a861 100644
--- a/tests/src/Kernel/JsonldContextGeneratorTest.php
+++ b/tests/src/Kernel/JsonldContextGeneratorTest.php
@@ -24,7 +24,6 @@ class JsonldContextGeneratorTest extends KernelTestBase {
     'rdf_test_namespaces',
     'serialization',
     'system',
-    'typed_data',
   ];
 
 
diff --git a/tests/src/Kernel/JsonldHookTest.php b/tests/src/Kernel/JsonldHookTest.php
new file mode 100644
index 0000000..e98eb54
--- /dev/null
+++ b/tests/src/Kernel/JsonldHookTest.php
@@ -0,0 +1,49 @@
+<?php
+
+namespace Drupal\Tests\jsonld\Kernel;
+
+/**
+ * Class JsonldHookTest.
+ *
+ * @package Drupal\Tests\jsonld\Kernel
+ * @group jsonld
+ */
+class JsonldHookTest extends JsonldKernelTestBase {
+
+  public static $modules = [
+    'entity',
+    'entity_test',
+    'hal',
+    'jsonld',
+    'rdf',
+    'rdf_test_namespaces',
+    'serialization',
+    'system',
+    'json_alter_normalize_hooks',
+  ];
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setUp() {
+    parent::setUp();
+    \Drupal::service('router.builder')->rebuild();
+  }
+
+  /**
+   * Test hook alter.
+   */
+  public function testAlterNormalizedJsonld() {
+
+    list($entity, $expected) = $this->generateTestEntity();
+    $expected['@graph'][] = [
+      "@id" => "json_alter_normalize_hooks",
+      "http://purl.org/dc/elements/1.1/title" => "The hook is tested.",
+    ];
+
+    $normalized = $this->serializer->normalize($entity, $this->format);
+    $this->assertEquals($expected, $normalized, "Did not normalize and call hooks correctly.");
+
+  }
+
+}
diff --git a/tests/src/Kernel/JsonldKernelTestBase.php b/tests/src/Kernel/JsonldKernelTestBase.php
index 4f3d5bd..e4cadb3 100644
--- a/tests/src/Kernel/JsonldKernelTestBase.php
+++ b/tests/src/Kernel/JsonldKernelTestBase.php
@@ -4,6 +4,7 @@
 
 use Drupal\Core\Cache\MemoryBackend;
 use Drupal\Core\Entity\EntityInterface;
+use Drupal\entity_test\Entity\EntityTest;
 use Drupal\field\Entity\FieldConfig;
 use Drupal\field\Entity\FieldStorageConfig;
 use Drupal\jsonld\Encoder\JsonldEncoder;
@@ -18,6 +19,7 @@
 use Drupal\serialization\EntityResolver\ChainEntityResolver;
 use Drupal\serialization\EntityResolver\TargetIdResolver;
 use Drupal\serialization\EntityResolver\UuidResolver;
+use Drupal\user\Entity\User;
 use Symfony\Component\Serializer\Serializer;
 
 /**
@@ -181,10 +183,122 @@ protected function getEntityUri(EntityInterface $entity) {
     // Some entity types don't provide a canonical link template, at least call
     // out to ->url().
     if ($entity->isNew() || !$entity->hasLinkTemplate('canonical')) {
-      return $entity->url('canonical', []);
+      return $entity->toUrl('canonical', []);
     }
-    $url = $entity->urlInfo('canonical', ['absolute' => TRUE]);
+    $url = $entity->toUrl('canonical', ['absolute' => TRUE]);
     return $url->setRouteParameter('_format', 'jsonld')->toString();
   }
 
+  /**
+   * Generate a test entity and the expected normalized array.
+   *
+   * @return array
+   *   with [ the entity, the normalized array ].
+   */
+  protected function generateTestEntity() {
+    $target_entity = EntityTest::create([
+      'name' => $this->randomMachineName(),
+      'langcode' => 'en',
+      'field_test_entity_reference' => NULL,
+    ]);
+    $target_entity->save();
+
+    $target_user = User::create([
+      'name' => $this->randomMachineName(),
+      'langcode' => 'en',
+    ]);
+    $target_user->save();
+
+    rdf_get_mapping('entity_test', 'entity_test')->setBundleMapping(
+      [
+        'types' => [
+          "schema:ImageObject",
+        ],
+      ])->setFieldMapping('field_test_text', [
+        'properties' => ['dc:description'],
+      ])->setFieldMapping('user_id', [
+        'properties' => ['schema:author'],
+      ])->setFieldMapping('modified', [
+        'properties' => ['schema:dateModified'],
+        'datatype' => 'xsd:dateTime',
+      ])->save();
+
+    $tz = new \DateTimeZone('UTC');
+    $dt = new \DateTime(NULL, $tz);
+    $created = $dt->format("U");
+    $created_iso = $dt->format(\DateTime::W3C);
+    // Create an entity.
+    $values = [
+      'langcode' => 'en',
+      'name' => $this->randomMachineName(),
+      'type' => 'entity_test',
+      'bundle' => 'entity_test',
+      'user_id' => $target_user->id(),
+      'created' => [
+        'value' => $created,
+      ],
+      'field_test_text' => [
+        'value' => $this->randomMachineName(),
+        'format' => 'full_html',
+      ],
+      'field_test_entity_reference' => [
+        'target_id' => $target_entity->id(),
+      ],
+    ];
+
+    $entity = EntityTest::create($values);
+    $entity->save();
+
+    $expected = [
+      "@graph" => [
+        [
+          "@id" => $this->getEntityUri($entity),
+          "@type" => [
+            'http://schema.org/ImageObject',
+          ],
+          "http://purl.org/dc/terms/references" => [
+            [
+              "@id" => $this->getEntityUri($target_entity),
+            ],
+          ],
+          "http://purl.org/dc/terms/description" => [
+            [
+              "@type" => "http://www.w3.org/2001/XMLSchema#string",
+              "@value" => $values['field_test_text']['value'],
+            ],
+          ],
+          "http://purl.org/dc/terms/title" => [
+            [
+              "@type" => "http://www.w3.org/2001/XMLSchema#string",
+              "@value" => $values['name'],
+            ],
+          ],
+          "http://schema.org/author" => [
+            [
+              "@id" => $this->getEntityUri($target_user),
+            ],
+          ],
+          "http://schema.org/dateCreated" => [
+            [
+              "@type" => "http://www.w3.org/2001/XMLSchema#dateTime",
+              "@value" => $created_iso,
+            ],
+          ],
+        ],
+        [
+          "@id" => $this->getEntityUri($target_user),
+          "@type" => "http://localhost/rest/type/user/user",
+        ],
+        [
+          "@id" => $this->getEntityUri($target_entity),
+          "@type" => [
+            "http://schema.org/ImageObject",
+          ],
+        ],
+      ],
+    ];
+
+    return [$entity, $expected];
+  }
+
 }
diff --git a/tests/src/Kernel/Normalizer/ContentEntityNormalizerTests.php b/tests/src/Kernel/Normalizer/ContentEntityNormalizerTests.php
index 810b2e3..15908ec 100644
--- a/tests/src/Kernel/Normalizer/ContentEntityNormalizerTests.php
+++ b/tests/src/Kernel/Normalizer/ContentEntityNormalizerTests.php
@@ -2,9 +2,7 @@
 
 namespace Drupal\Tests\jsonld\Kernel\Normalizer;
 
-use Drupal\entity_test\Entity\EntityTest;
 use Drupal\Tests\jsonld\Kernel\JsonldKernelTestBase;
-use Drupal\user\Entity\User;
 
 /**
  * Class ContentEntityTests.
@@ -34,107 +32,7 @@ protected function setUp() {
    */
   public function testSimpleNormalizeJsonld() {
 
-    $target_entity = EntityTest::create([
-      'name' => $this->randomMachineName(),
-      'langcode' => 'en',
-      'field_test_entity_reference' => NULL,
-    ]);
-    $target_entity->save();
-
-    $target_user = User::create([
-      'name' => $this->randomMachineName(),
-      'langcode' => 'en',
-    ]);
-    $target_user->save();
-
-    rdf_get_mapping('entity_test', 'entity_test')->setBundleMapping(
-      [
-        'types' => [
-          "schema:ImageObject",
-        ],
-      ])->setFieldMapping('field_test_text', [
-        'properties' => ['dc:description'],
-      ])->setFieldMapping('user_id', [
-        'properties' => ['schema:author'],
-      ])->setFieldMapping('modified', [
-        'properties' => ['schema:dateModified'],
-        'datatype' => 'xsd:dateTime',
-      ])->save();
-
-    $tz = new \DateTimeZone('UTC');
-    $dt = new \DateTime(NULL, $tz);
-    $created = $dt->format("U");
-    $created_iso = $dt->format(\DateTime::W3C);
-    // Create an entity.
-    $values = [
-      'langcode' => 'en',
-      'name' => $this->randomMachineName(),
-      'type' => 'entity_test',
-      'bundle' => 'entity_test',
-      'user_id' => $target_user->id(),
-      'created' => [
-        'value' => $created,
-      ],
-      'field_test_text' => [
-        'value' => $this->randomMachineName(),
-        'format' => 'full_html',
-      ],
-      'field_test_entity_reference' => [
-        'target_id' => $target_entity->id(),
-      ],
-    ];
-
-    $entity = EntityTest::create($values);
-    $entity->save();
-
-    $expected = [
-      "@graph" => [
-        [
-          "@id" => $this->getEntityUri($entity),
-          "@type" => [
-            'http://schema.org/ImageObject',
-          ],
-          "http://purl.org/dc/terms/references" => [
-            [
-              "@id" => $this->getEntityUri($target_entity),
-            ],
-          ],
-          "http://purl.org/dc/terms/description" => [
-            [
-              "@type" => "http://www.w3.org/2001/XMLSchema#string",
-              "@value" => $values['field_test_text']['value'],
-            ],
-          ],
-          "http://purl.org/dc/terms/title" => [
-            [
-              "@type" => "http://www.w3.org/2001/XMLSchema#string",
-              "@value" => $values['name'],
-            ],
-          ],
-          "http://schema.org/author" => [
-            [
-              "@id" => $this->getEntityUri($target_user),
-            ],
-          ],
-          "http://schema.org/dateCreated" => [
-            [
-              "@type" => "http://www.w3.org/2001/XMLSchema#dateTime",
-              "@value" => $created_iso,
-            ],
-          ],
-        ],
-        [
-          "@id" => $this->getEntityUri($target_user),
-          "@type" => "http://localhost/rest/type/user/user",
-        ],
-        [
-          "@id" => $this->getEntityUri($target_entity),
-          "@type" => [
-            "http://schema.org/ImageObject",
-          ],
-        ],
-      ],
-    ];
+    list($entity, $expected) = $this->generateTestEntity();
 
     $normalized = $this->serializer->normalize($entity, $this->format);
     $this->assertEquals($expected, $normalized, "Did not normalize correctly.");