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An AJAX endpoint in the TYPO3 backend is usually implemented as a method in a regular controller. The method receives a request object implementing the Psr\Http\Message\ServerRequestInterface, which allows to access all aspects of the requests and returns an appropriate response in a normalized way. This approach is standardized as PSR-7.

Create a Controller

By convention, a controller is placed within the extension's Controller directory, optionally in a subdirectory. To have such controller, create a new ExampleController in Classes/Controller/ExampleController.php inside your extension.

The controller doesn't need that much logic right now. We'll create a method called doSomethingAction() which will be our AJAX endpoint. And we inject the ResponseFactoryInterface later needed to create our response. See Creating Response Objects in PSR 17.

declare(strict_types = 1);

namespace Vendor\MyExtension\Controller;

use Psr\Http\Message\ResponseFactoryInterface;
use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;

class ExampleController
   /** @var ResponseFactoryInterface */
   private $responseFactory;

   public function __construct(ResponseFactoryInterface $responseFactory)
      $this->responseFactory = $responseFactory;

   public function doSomethingAction(ServerRequestInterface $request): ResponseInterface
        // TODO: return ResponseInterface

In its current state, the method doesn't do anything yet. We can add a very generic handling that exponentiates an incoming number by 2. The incoming value will be passed as a query string argument named input.

public function doSomethingAction(ServerRequestInterface $request): ResponseInterface
    $input = $request->getQueryParams()['input'] ?? null;
    if ($input === null) {
        throw new \InvalidArgumentException('Please provide a number', 1580585107);

    $result = $input ** 2;
    // TODO: return ResponseInterface


This is a really simple example. Something like this should not be used in production, as such feature is available in JavaScript as well.

We have computed our result by using the exponentiation operator, but we don't do anything with it yet. It's time to build a proper response. A response implements the Psr\Http\Message\ResponseInterface and its constructor accepts the following arguments:


| Condition: required | Type: string |

The content of the response.


| Condition: optional | Type: int | Default: 200 |

The HTTP status code of the response. The default of 200 means OK.


| Condition: optional | Type: array | Default: '[]' |

Headers to be sent with the response.


| Condition: optional | Type: string | Default: '' |

A reason for the given status code. If omitted, the default for the used status code will be used.

public function doSomethingAction(ServerRequestInterface $request): ResponseInterface
   // our previous computation

   $data = ['result' => $result];
   $response = $this->responseFactory->createResponse()
      ->withHeader('Content-Type', 'application/json; charset=utf-8');
   return $response;

Register the Endpoint

The endpoint must be registered as route. Create a file called Configuration/Backend/AjaxRoutes.php in your extension. The file basically just returns an array of route definitions. Every route in this file will be exposed to JavaScript automatically. Let's register our endpoint now:


return [
    'example_dosomething' => [
        'path' => '/example/do-something',
        'target' => \Vendor\MyExtension\Controller\ExampleController::class . '::doSomethingAction',

The naming of the key example_dosomething and path /example/do-something are up to you, but should contain the controller name and action name to avoid potential conflicts with other existing routes.

For further reading, take a look at Backend Routing.


Flushing caches is mandatory after modifying any route definition.

Use in AJAX

Since the route is registered in AjaxRoutes.php its exposed to JavaScript now and stored in the global TYPO3.settings.ajaxUrls object identified by the used key in the registration. In this example it's TYPO3.settings.ajaxUrls.example_dosomething.

You are now free to use the endpoint in any of your AJAX calls. To complete this example, we'll ask the server to compute our input and write the result into the console.

require(['TYPO3/CMS/Core/Ajax/AjaxRequest'], function (AjaxRequest) {
  // Generate a random number between 1 and 32
  const randomNumber = Math.ceil(Math.random() * 32);
  new AjaxRequest(TYPO3.settings.ajaxUrls.example_dosomething)
    .withQueryArguments({input: randomNumber})
    .then(async function (response) {
    const resolved = await response.resolve();