diff --git a/lib/API/MP/v1/API.php b/lib/API/MP/v1/API.php
index 97ff9eb4a5..648f109c7f 100644
--- a/lib/API/MP/v1/API.php
+++ b/lib/API/MP/v1/API.php
@@ -2,8 +2,6 @@
 
 namespace MailPoet\API\MP\v1;
 
-use MailPoet\CustomFields\ApiDataSanitizer;
-use MailPoet\Models\CustomField;
 use MailPoet\Models\Segment;
 use MailPoet\Models\Subscriber;
 use MailPoet\Models\SubscriberSegment;
@@ -28,89 +26,38 @@ class API {
   /** @var RequiredCustomFieldValidator */
   private $requiredCustomFieldValidator;
 
-  /** @var ApiDataSanitizer */
-  private $customFieldsDataSanitizer;
-
   /** @var WelcomeScheduler */
   private $welcomeScheduler;
 
   /** @var SettingsController */
   private $settings;
 
+  /** @var CustomFields */
+  private $customFields;
+
   public function __construct(
     NewSubscriberNotificationMailer $newSubscriberNotificationMailer,
     ConfirmationEmailMailer $confirmationEmailMailer,
     RequiredCustomFieldValidator $requiredCustomFieldValidator,
-    ApiDataSanitizer $customFieldsDataSanitizer,
     WelcomeScheduler $welcomeScheduler,
+    CustomFields $customFields,
     SettingsController $settings
   ) {
     $this->newSubscriberNotificationMailer = $newSubscriberNotificationMailer;
     $this->confirmationEmailMailer = $confirmationEmailMailer;
     $this->requiredCustomFieldValidator = $requiredCustomFieldValidator;
-    $this->customFieldsDataSanitizer = $customFieldsDataSanitizer;
     $this->welcomeScheduler = $welcomeScheduler;
     $this->settings = $settings;
+    $this->customFields = $customFields;
   }
 
   public function getSubscriberFields() {
-    $data = [
-      [
-        'id' => 'email',
-        'name' => __('Email', 'mailpoet'),
-        'type' => 'text',
-        'params' => [
-          'required' => '1',
-        ],
-      ],
-      [
-        'id' => 'first_name',
-        'name' => __('First name', 'mailpoet'),
-        'type' => 'text',
-        'params' => [
-          'required' => '',
-        ],
-      ],
-      [
-        'id' => 'last_name',
-        'name' => __('Last name', 'mailpoet'),
-        'type' => 'text',
-        'params' => [
-          'required' => '',
-        ],
-      ],
-    ];
-
-    $customFields = CustomField::selectMany(['id', 'name', 'type', 'params'])->findMany();
-    foreach ($customFields as $customField) {
-      $result = [
-        'id' => 'cf_' . $customField->id,
-        'name' => $customField->name,
-        'type' => $customField->type,
-      ];
-      if (is_serialized($customField->params)) {
-        $result['params'] = unserialize($customField->params);
-      } else {
-        $result['params'] = $customField->params;
-      }
-      $data[] = $result;
-    }
-
-    return $data;
+    return $this->customFields->getSubscriberFields();
   }
 
   public function addSubscriberField(array $data = []) {
     try {
-      $customField = CustomField::createOrUpdate($this->customFieldsDataSanitizer->sanitize($data));
-      $errors = $customField->getErrors();
-      if (!empty($errors)) {
-        throw new APIException('Failed to save a new subscriber field ' . join(', ', $errors), APIException::FAILED_TO_SAVE_SUBSCRIBER_FIELD);
-      }
-      $customField = CustomField::findOne($customField->id);
-      if (!$customField instanceof CustomField) {
-        throw new APIException('Failed to create a new subscriber field', APIException::FAILED_TO_SAVE_SUBSCRIBER_FIELD);
-      }
-      return $customField->asArray();
+      return $this->customFields->addSubscriberField($data);
     } catch (\InvalidArgumentException $e) {
       throw new APIException($e->getMessage(), $e->getCode(), $e);
     }
@@ -288,7 +235,7 @@ class API {
     }
 
     // separate data into default and custom fields
-    list($defaultFields, $customFields) = Subscriber::extractCustomFieldsFromFromObject($subscriber);
+    [$defaultFields, $customFields] = Subscriber::extractCustomFieldsFromFromObject($subscriber);
 
     // filter out all incoming data that we don't want to change, like status ...
     $defaultFields = array_intersect_key($defaultFields, array_flip(['email', 'first_name', 'last_name', 'subscribed_ip']));
diff --git a/lib/API/MP/v1/CustomFields.php b/lib/API/MP/v1/CustomFields.php
new file mode 100644
index 0000000000..1a6be44ef6
--- /dev/null
+++ b/lib/API/MP/v1/CustomFields.php
@@ -0,0 +1,74 @@
+<?php declare(strict_types = 1);
+
+namespace MailPoet\API\MP\v1;
+
+use MailPoet\CustomFields\ApiDataSanitizer;
+use MailPoet\Models\CustomField;
+
+class CustomFields {
+  /** @var ApiDataSanitizer */
+  private $customFieldsDataSanitizer;
+
+  public function __construct(ApiDataSanitizer $customFieldsDataSanitizer) {
+    $this->customFieldsDataSanitizer = $customFieldsDataSanitizer;
+  }
+
+  public function getSubscriberFields(): array {
+    $data = [
+      [
+        'id' => 'email',
+        'name' => __('Email', 'mailpoet'),
+        'type' => 'text',
+        'params' => [
+          'required' => '1',
+        ],
+      ],
+      [
+        'id' => 'first_name',
+        'name' => __('First name', 'mailpoet'),
+        'type' => 'text',
+        'params' => [
+          'required' => '',
+        ],
+      ],
+      [
+        'id' => 'last_name',
+        'name' => __('Last name', 'mailpoet'),
+        'type' => 'text',
+        'params' => [
+          'required' => '',
+        ],
+      ],
+    ];
+
+    $customFields = CustomField::selectMany(['id', 'name', 'type', 'params'])->findMany();
+    foreach ($customFields as $customField) {
+      $result = [
+        'id' => 'cf_' . $customField->id,
+        'name' => $customField->name,
+        'type' => $customField->type,
+      ];
+      if (is_serialized($customField->params)) {
+        $result['params'] = unserialize($customField->params);
+      } else {
+        $result['params'] = $customField->params;
+      }
+      $data[] = $result;
+    }
+
+    return $data;
+  }
+
+  public function addSubscriberField(array $data = []): array {
+    $customField = CustomField::createOrUpdate($this->customFieldsDataSanitizer->sanitize($data));
+    $errors = $customField->getErrors();
+    if (!empty($errors)) {
+      throw new APIException('Failed to save a new subscriber field ' . join(', ', $errors), APIException::FAILED_TO_SAVE_SUBSCRIBER_FIELD);
+    }
+    $customField = CustomField::findOne($customField->id);
+    if (!$customField instanceof CustomField) {
+      throw new APIException('Failed to create a new subscriber field', APIException::FAILED_TO_SAVE_SUBSCRIBER_FIELD);
+    }
+    return $customField->asArray();
+  }
+}
diff --git a/lib/DI/ContainerConfigurator.php b/lib/DI/ContainerConfigurator.php
index 651f23e5da..fac0c2d3e9 100644
--- a/lib/DI/ContainerConfigurator.php
+++ b/lib/DI/ContainerConfigurator.php
@@ -55,6 +55,7 @@ class ContainerConfigurator implements IContainerConfigurator {
       ->setAutowired(true)
       ->setPublic(true);
     $container->autowire(\MailPoet\API\JSON\ErrorHandler::class)->setPublic(true);
+    $container->autowire(\MailPoet\API\MP\v1\CustomFields::class)->setPublic(true);
     $container->autowire(\MailPoet\API\MP\v1\API::class)->setPublic(true);
     $container->autowire(\MailPoet\API\JSON\v1\Analytics::class)->setPublic(true);
     $container->autowire(\MailPoet\API\JSON\v1\AutomatedLatestContent::class)->setPublic(true);
diff --git a/tests/integration/API/MP/APITest.php b/tests/integration/API/MP/APITest.php
index 1d7d6dccaa..d7357aea4f 100644
--- a/tests/integration/API/MP/APITest.php
+++ b/tests/integration/API/MP/APITest.php
@@ -5,6 +5,7 @@ namespace MailPoet\Test\API\MP;
 use Codeception\Stub;
 use Codeception\Stub\Expected;
 use Codeception\Util\Fixtures;
+use MailPoet\API\MP\v1\CustomFields;
 use MailPoet\CustomFields\ApiDataSanitizer;
 use MailPoet\CustomFields\CustomFieldsRepository;
 use MailPoet\Entities\CustomFieldEntity;
@@ -38,8 +39,8 @@ class APITest extends \MailPoetTest {
       Stub::makeEmpty(NewSubscriberNotificationMailer::class, ['send']),
       Stub::makeEmpty(ConfirmationEmailMailer::class, ['sendConfirmationEmail']),
       $this->diContainer->get(RequiredCustomFieldValidator::class),
-      Stub::makeEmpty(ApiDataSanitizer::class),
       Stub::makeEmpty(WelcomeScheduler::class),
+      $this->diContainer->get(CustomFields::class),
       SettingsController::getInstance()
     );
   }
@@ -288,8 +289,8 @@ class APITest extends \MailPoetTest {
       $notificationMailer,
       $this->makeEmpty(ConfirmationEmailMailer::class),
       $this->makeEmpty(RequiredCustomFieldValidator::class),
-      $this->makeEmpty(ApiDataSanitizer::class),
       Stub::makeEmpty(WelcomeScheduler::class),
+      $this->diContainer->get(CustomFields::class),
       SettingsController::getInstance()
     );
     $API->subscribeToLists($subscriber->email, $segments, ['send_confirmation_email' => false, 'skip_subscriber_notification' => true]);
@@ -301,8 +302,8 @@ class APITest extends \MailPoetTest {
       $notificationMailer,
       $this->makeEmpty(ConfirmationEmailMailer::class),
       $this->makeEmpty(RequiredCustomFieldValidator::class),
-      $this->makeEmpty(ApiDataSanitizer::class),
       Stub::makeEmpty(WelcomeScheduler::class),
+      $this->diContainer->get(CustomFields::class),
       SettingsController::getInstance()
     );
     $API->subscribeToLists($subscriber->email, $segments, ['send_confirmation_email' => false, 'skip_subscriber_notification' => false]);
@@ -560,8 +561,8 @@ class APITest extends \MailPoetTest {
       Stub::makeEmpty(NewSubscriberNotificationMailer::class, ['send']),
       Stub::makeEmpty(ConfirmationEmailMailer::class, ['sendConfirmationEmailOnce']),
       $this->diContainer->get(RequiredCustomFieldValidator::class),
-      Stub::makeEmpty(ApiDataSanitizer::class),
       $welcomeScheduler,
+      $this->diContainer->get(CustomFields::class),
       Stub::makeEmpty(SettingsController::class)
     );
     $subscriber = [