A webhook is a URL of another system that Jenkins calls automatically as soon as something happens, here: a failed test or build is claimed (someone takes responsibility) or unclaimed (the claim is released). Jenkins sends a small JSON message via HTTP POST to that URL, so external tools such as chat bots, ticket systems or dashboards can react immediately without polling Jenkins.

You can configure several webhooks and restrict each one to claim and/or unclaim events and to tests and/or builds. An optional secret lets the receiver verify that a message really comes from this Jenkins.

Sending is asynchronous and best effort: if a webhook is unreachable or answers with an error, this is only written to the Jenkins log. Claiming itself is never blocked or broken by a webhook. If no webhook is configured, nothing is sent.

The structure of the message is described in the help of the Payload format entry of each webhook.