A Webhook is an HTTP request used to provide push notifications. O21Pay sends Webhooks to inform you programmatically about events related to your merchant (shop).
To receive Webhooks from O21Pay, configure a dedicated endpoint on your server as a webhook listener that can receive POST requests, and then configure the URL of that endpoint on the O21Pay dashboard.
You can also test webhooks without configuring your own endpoint by following the instructions in the Testing Webhooks section of the Sandbox.