I already asked for this via the support, but it might be also relevant for others, so I post it here.
I like to see webhooks in TestRail, so that one can receive notifications for a defined set of actions, like creating or updating a test case. Adding new results to a test or similar.
This is how Bitbucket offers webhooks:
which I think is quite nice. One can define the endpoint the request is sent to and a set of actions that triggers such a request.
The request could be JSON or similar and containing information about the corresponding action.
Currently the only possibility to receive such notification, is to poll the server constantly and creating an enormous overhead with it.
Please consider this in a future release of TestRail