HTTP 409 Conflict indicates the request conflicts with the current state of the target resource. This is commonly used for: concurrent update conflicts (optimistic locking), unique constraint violations (duplicate email on registration), state machine violations (trying to publish an already-published article), and version conflicts in collaborative editing. The response body should explain the conflict and ideally how to resolve it.
Response includes the status code, standard headers (including Content-Type), and a small diagnostic JSON body describing the request and returned status.
Simulator URL (copy in the app after load — not a normal link):
https://httpstatus.com/api/status/409
Example request:
curl -i "https://httpstatus.com/api/status/409"