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Sunset Header

The Sunset HTTP header field (RFC 8594) is an informational IETF specification that allows servers to communicate to clients that a URI is likely to become unresponsive at a specified future point in time. Published in May 2019, it provides a standardized mechanism for API deprecation signaling, enabling clients to plan migrations before service retirement. The header value is an HTTP-date timestamp following RFC 7231 syntax. A complementary sunset link relation type allows resources to reference documentation covering the sunset policy, migration guidance, and alternatives. RFC 9745 (Deprecation HTTP Header Field) extends this pattern by providing a two-phase deprecation + sunset lifecycle where Deprecation marks the start of deprecation and Sunset marks the end-of-life. These two headers are widely adopted in REST API governance practices and API lifecycle management tooling.

2 APIs 0 Features
API DeprecationHTTP HeadersRFC 8594RFC 9745API LifecycleREST APIsStandards

APIs

Sunset Header (RFC 8594)

The Sunset HTTP header field (RFC 8594) communicates the deprecation timeline of API endpoints to consumers. The header value is an HTTP-date timestamp indicating when a URI is ...

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...

Semantic Vocabularies

Sunset Header Context

0 classes · 15 properties

JSON-LD

Resources

🔗
Website
Website
🔗
IETF Specification
IETF Specification

Sources

apis.yml Raw ↑ 
aid: sunset-header
name: Sunset Header
description: >-
  The Sunset HTTP header field (RFC 8594) is an informational IETF specification
  that allows servers to communicate to clients that a URI is likely to become
  unresponsive at a specified future point in time. Published in May 2019, it
  provides a standardized mechanism for API deprecation signaling, enabling
  clients to plan migrations before service retirement. The header value is an
  HTTP-date timestamp following RFC 7231 syntax. A complementary sunset link
  relation type allows resources to reference documentation covering the sunset
  policy, migration guidance, and alternatives. RFC 9745 (Deprecation HTTP Header
  Field) extends this pattern by providing a two-phase deprecation + sunset
  lifecycle where Deprecation marks the start of deprecation and Sunset marks
  the end-of-life. These two headers are widely adopted in REST API governance
  practices and API lifecycle management tooling.
type: Index
image: https://kinlane-productions.s3.amazonaws.com/apis-json/apis-json-logo.jpg
tags:
  - API Deprecation
  - HTTP Headers
  - RFC 8594
  - RFC 9745
  - API Lifecycle
  - REST APIs
  - Standards
url: >-
  https://raw.githubusercontent.com/api-evangelist/sunset-header/refs/heads/main/apis.yml
created: '2026-03-29'
modified: '2026-05-02'
specificationVersion: '0.19'
apis:
  - aid: sunset-header:sunset-header
    name: Sunset Header (RFC 8594)
    description: >-
      The Sunset HTTP header field (RFC 8594) communicates the deprecation
      timeline of API endpoints to consumers. The header value is an HTTP-date
      timestamp indicating when a URI is expected to become unresponsive. It is
      accompanied by a sunset link relation type for linking to deprecation
      documentation and migration guidance.
    humanURL: https://datatracker.ietf.org/doc/html/rfc8594
    tags:
      - HTTP Headers
      - API Deprecation
      - RFC 8594
      - Sunset
      - API Lifecycle
    properties:
      - type: Documentation
        url: https://datatracker.ietf.org/doc/html/rfc8594
      - type: Specification
        url: https://www.rfc-editor.org/rfc/rfc8594
  - 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
common:
  - type: Website
    url: https://datatracker.ietf.org/doc/html/rfc8594
  - type: IETF Specification
    url: https://www.rfc-editor.org/rfc/rfc8594
maintainers:
  - FN: Kin Lane
    email: [email protected]