Deprecation HTTP Header Field (RFC 9745)

RFC 9745 defines the Deprecation HTTP response header field, which signals to clients that a resource has been or will be deprecated. It complements the Sunset header by marking the start of the deprecation lifecycle. The header value is a structured date (Unix timestamp per RFC 9651). The Sunset timestamp, if present, must not be earlier than the Deprecation timestamp.

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API entry from apis.yml

apis.yml Raw ↑
aid: sunset-header:deprecation-header
name: Deprecation HTTP Header Field (RFC 9745)
description: RFC 9745 defines the Deprecation HTTP response header field, which signals to clients that
  a resource has been or will be deprecated. It complements the Sunset header by marking the start of
  the deprecation lifecycle. The header value is a structured date (Unix timestamp per RFC 9651). The
  Sunset timestamp, if present, must not be earlier than the Deprecation timestamp.
humanURL: https://www.rfc-editor.org/rfc/rfc9745.html
tags:
- HTTP Headers
- API Deprecation
- RFC 9745
- Deprecation
- API Lifecycle
properties:
- type: Documentation
  url: https://www.rfc-editor.org/rfc/rfc9745.html
- type: Specification
  url: https://datatracker.ietf.org/doc/html/rfc9745