Owners and admins can point a project at other systems: a signed JSON POST (HMAC-SHA256 of the body) when tickets, comments, releases or sprints change, filtered by event or family. Deliveries are retried a couple of times, the last one is shown, and a ping can be sent from the settings. Private addresses are refused unless WEBHOOKS_ALLOW_PRIVATE is set. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>