diff --git a/src/Form/JobItemForm.php b/src/Form/JobItemForm.php
index 976741f..84ad74e 100644
--- a/src/Form/JobItemForm.php
+++ b/src/Form/JobItemForm.php
@@ -329,31 +329,32 @@ class JobItemForm extends TmgmtFormBase {
       $translator_ui->reviewFormSubmit($form, $form_state, $item);
     }
     // Write changes back to item.
+    $data_service = \Drupal::service('tmgmt.data');
     foreach ($form_state->getValues() as $key => $value) {
       if (is_array($value) && isset($value['translation'])) {
         // Update the translation, this will only update the translation in case
         // it has changed. We have two different cases, the first is for nested
         // texts.
-        if (is_array($value['translation'])) {
-          $data = array(
-            '#text' => $value['translation']['value'],
-            '#origin' => 'local',
-          );
+        $original_text = is_array($value['translation']) ? $value['translation']['value'] : $value['translation'];
+        $text = $original_text;
+        // Initialise the empty translation with empty segment-only tags.
+        if ($text == '') {
+          $text = '';
         }
-        else {
-          $data = array(
-            '#text' => $value['translation'],
-            '#origin' => 'local',
-          );
-        }
-        if ($data['#text'] == '' && $item->isActive() && $form_state->getTriggeringElement()['#value'] != '✓') {
+        // Unmask the translation's HTML tags.
+        $data_item = $item->getData($data_service->ensureArrayKey($key));
+        $contexts = [$data_item, $this->entity];
+        \Drupal::moduleHandler()->alter('tmgmt_data_item_text_input', $text, $contexts);
+
+        $data = [
+          '#text' => $text,
+          '#origin' => 'local',
+        ];
+        if ($original_text == '' && $item->isActive() && $form_state->getTriggeringElement()['#value'] != '✓') {
           $data = NULL;
           continue;
         }
-
-        $data_service = \Drupal::service('tmgmt.data');
-        $current_data_status = $item->getData($data_service->ensureArrayKey($key))['#status'];
-
+        $current_data_status = $data_item['#status'];
         $item->addTranslatedData($data, $key, $current_data_status);
       }
     }
@@ -475,6 +476,17 @@ class JobItemForm extends TmgmtFormBase {
         $rows = min($rows, 15);
         $rows = max($rows, 3);
 
+        // Mask HTML-tag of source's text and translation's text, if available.
+        $source_text = $data_item['#text'];
+        // If translation is empty, initialize it with empty segment-only tags.
+        // @todo: Add context to show that this is a translation.
+        $translation_text = isset($data_item['#translation']['#text']) ? $data_item['#translation']['#text'] : '';
+        $contexts = [$data_item, $this->entity];
+        \Drupal::moduleHandler()->alter('tmgmt_data_item_text_output', $source_text, $translation_text, $contexts);
+        $data_item['#text'] = $source_text;
+        $data_item['#translation']['#text'] = $translation_text;
+
+
         // Build source and translation areas.
         $item_element = $this->buildSource($item_element, $data_item, $rows, $form_state);
         $item_element = $this->buildTranslation($item_element, $data_item, $rows, $form_state, $is_preliminary);
diff --git a/src/Tests/TMGMTUiReviewTest.php b/src/Tests/TMGMTUiReviewTest.php
index 114c19c..811fd04 100644
--- a/src/Tests/TMGMTUiReviewTest.php
+++ b/src/Tests/TMGMTUiReviewTest.php
@@ -467,7 +467,7 @@ class TMGMTUiReviewTest extends EntityTestBase {
 
     // Create the node.
     $settings = array(
-      'title' => $this->randomMachineName(),
+      'title' => 'First node',
       'type' => 'test_bundle',
       'body_test' => array(
         $this->randomMachineName(),
@@ -487,7 +487,11 @@ class TMGMTUiReviewTest extends EntityTestBase {
     $job_item->save();
 
     // Access to the review form.
-    $this->drupalGet('admin/tmgmt/items/1');
+    $this->drupalGet('admin/tmgmt/items/'. $job_item->id());
+    // Check that 'hook_tmgmt_data_item_text_output_alter' has been called.
+    $data = $job_item->getData();
+    $this->assertEqual($data['title'][0]['value']['#text'], 'First node');
+    $this->assertFieldByName('title|0|value[source]', 'Second node');
 
     // Test that all the items are being displayed.
     $this->assertRaw('name="title|0|value[source]"');
@@ -530,6 +534,21 @@ class TMGMTUiReviewTest extends EntityTestBase {
     $this->assertEqual($label[0], 'Alternative text');
     $label = $this->xpath('//*[@id="tmgmt-ui-element-image-test-single-wrapper"]/table/tbody/tr[3]/td[1]/div[1]/label');
     $this->assertEqual($label[0], 'Title');
+
+    // Check 'hook_tmgmt_data_item_text_input_alter' has been called on saving.
+    $this->drupalPostForm(NULL, ['title|0|value[translation]' => 'Second node translation'], 'Save');
+    // Clean the storage and get the updated job item data.
+    \Drupal::entityTypeManager()->getStorage('tmgmt_job_item')->resetCache();
+    $job_item = JobItem::load($job_item->id());
+    $data = $job_item->getData();
+    $this->assertEqual($data['title'][0]['value']['#text'], 'First node');
+    $this->assertEqual($data['title'][0]['value']['#translation']['#text'], 'First node translation');
+
+    // Access to the review form.
+    $this->drupalGet('admin/tmgmt/items/'. $job_item->id());
+    // Check that 'hook_tmgmt_data_item_text_output_alter' has been called.
+    $this->assertFieldByName('title|0|value[source]', 'Second node');
+    $this->assertFieldByName('title|0|value[translation]', 'Second node translation');
   }
 
   /**
diff --git a/tmgmt.api.php b/tmgmt.api.php
index b33db9e..48c1858 100644
--- a/tmgmt.api.php
+++ b/tmgmt.api.php
@@ -6,6 +6,7 @@
  */
 
 use Drupal\tmgmt\JobInterface;
+use Drupal\tmgmt\JobItemInterface;
 
 /**
  * @addtogroup tmgmt_source
@@ -297,3 +298,30 @@ function hook_tmgmt_job_after_request_translation(JobInterface $job) {
     }
   }
 }
+
+/**
+ * Allows to alter a text's segment masking the HTML tags from a tmgmt-tag.
+ *
+ * @param string $source_text
+ *   The source's text segment to alter.
+ * @param string $translation_text
+ *   The translation's text segment to alter.
+ * @param array $context
+ *   An array containing $data_item and $job_item contexts.
+ */
+function hook_tmgmt_data_item_text_output_alter(&$source_text, &$translation_text, array $context) {
+  $source_text = str_replace('First', 'Second', $source_text);
+  $translation_text = str_replace('First', 'Second', $translation_text);
+}
+
+/**
+ * Allows to alter a text's segment unmasking the HTML tags into a tmgmt-tag.
+ *
+ * @param string $translation_text
+ *   The translation's text segment to alter.
+ * @param array $context
+ *   An array containing $data_item and $job_item contexts.
+ */
+function hook_tmgmt_data_item_text_input_alter(&$translation_text, array $context) {
+  $translation_text = str_replace('Second', 'First', $translation_text);
+}
diff --git a/tmgmt_test/tmgmt_test.module b/tmgmt_test/tmgmt_test.module
index 818ebea..037fe64 100644
--- a/tmgmt_test/tmgmt_test.module
+++ b/tmgmt_test/tmgmt_test.module
@@ -6,6 +6,7 @@
  */
 
 use Drupal\tmgmt\JobInterface;
+use Drupal\tmgmt\JobItemInterface;
 
 /**
  * Implements hook_tmgmt_translator_info_alter().
@@ -43,3 +44,18 @@ function tmgmt_test_tmgmt_file_text_processor_plugin_info() {
     ),
   );
 }
+
+/**
+ * Implements hook_tmgmt_data_item_text_output_alter().
+ */
+function tmgmt_test_tmgmt_data_item_text_output_alter(&$source_text, &$translation_text, array $context) {
+  $source_text = str_replace('First', 'Second', $source_text);
+  $translation_text = str_replace('First', 'Second', $translation_text);
+}
+
+/**
+ * Implements hook_tmgmt_data_item_text_input_alter().
+ */
+function tmgmt_test_tmgmt_data_item_text_input_alter(&$translation_text, array $context) {
+  $translation_text = str_replace('Second', 'First', $translation_text);
+}