Sunset header, explained
Its value is an HTTP date, for example Sunset: Wed, 01 Jul 2026 00:00:00 GMT. It is often paired with the Deprecation header (RFC 9745) and a Link header pointing to migration documentation.
Because it is machine-readable, SDKs, gateways and monitoring can warn developers about upcoming removals long before anything breaks.
Related terms
- API deprecation: API deprecation is the formal announcement that an endpoint, field or version is going away, with a timeline for clients to migrate before it is removed.
- API versioning: API versioning is the practice of exposing multiple versions of an API at once so providers can ship breaking changes while existing clients keep using the version they were built for.
- API gateway: An API gateway is a server that sits in front of one or more APIs and handles cross-cutting concerns such as routing, authentication, rate limiting, logging and version routing.