What is an Accept-Patch header?
Advertises which patch document formats a resource accepts on a PATCH request.
Accept-Patch lets a website's API tell clients which patch document formats (like JSON Patch) a resource supports for partial updates, so a client doesn't have to guess or fall back to trial and error. It's a fairly specialised header, mostly relevant to REST APIs that support PATCH as a first-class operation rather than general-purpose websites.
Common use case
A REST API advertises support for the JSON Patch format via Accept-Patch, so client libraries know they can send a structured list of partial-update operations rather than a full replacement document.
Example
Accept-Patch: application/json-patch+jsonHistory
Standardised in RFC 5789 (2010), the same specification that formally defined the PATCH method itself.
Did you know?
It's often sent alongside the Allow header on an OPTIONS response, giving a client the complete picture of both which methods and which patch formats a resource supports in one round trip.