Callbacks are a way to make one or more HTTP calls after an entering request reaches your route. This is useful to call other APIs or micro-services or to trigger a webhook.
Callbacks are fully configurable and are created at the environment level, like the data buckets.
To create a new callback, open the Callbacks options by clicking on the tab at the top of the window:

Add a new callback by clicking on the "plus" button:

The callback configuration interface is very similar to the route response interface. You can configure the callback's name, description, method, URL, body, and headers:
POST, PUT, and PATCH).