Sunset Header website screenshot

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...

Pricing Plans

Sunset Header Plans Pricing

3 plans

PLANS

Rate Limits

Sunset Header Rate Limits

5 limits

RATE LIMITS

FinOps

Sunset Header Finops

FINOPS

Semantic Vocabularies

Sunset Header Context

0 classes · 15 properties

JSON-LD

Example Payloads

Sunset Header Response Example

6 fields

EXAMPLE

Resources

🔗
DomainSecurity
DomainSecurity
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Website
Website
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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-images.s3.amazonaws.com/shared/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: DomainSecurity
  url: security/sunset-header-domain-security.yml
- 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: kin@apievangelist.com