# Sunset Header

**Canonical:** https://apis.io/providers/sunset-header/  
**Website:** https://datatracker.ietf.org/doc/html/rfc8594  
**APIs profiled:** 2

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.

## Kin Score — 14.0 / 100 (emerging)

Scored 2026-08-25 under rubric 0.14.0. Trend: flat (+0.0 from 14.0).

| Facet | Score |
|---|---|
| Discoverability | 59.3 |
| Contract Quality | 10.7 |
| Governance | 9.8 |
| Contract Governance | 9.8 |
| Operational Transparency | 7.9 |
| Developer Ergonomics | 0.0 |
| Commercial Clarity | 15.8 |
| Access Clarity | 15.8 |

## Agent readiness — 2.5 (human-only)

| Dimension | Value |
|---|---|
| Spec Presence | no |
| Agentic Access | no |
| Reversibility Documented | no |
| MCP Server | no |
| Auth Clarity | no |
| Idempotency | no |
| Error Semantics | no |
| OpenAPI Examples | no |
| Rate Limit Signal | documented |
| Event Surface Described | no |
| Agent Skills | no |
| Well Known Catalog | no |
| Consent Identity | no |
| Agent Card | no |
| Dry Run Mode | no |
| Delegated Identity | no |
| Protected Resource Metadata | no |
| Dynamic Client Registration | no |
| Agentic Commerce | no |

## Access

Freemium — onboarding: unknown, pricing: freemium, trial: no (confidence: medium).

## APIs (2)

- **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...

## Security (1)

- **Sunset Header Domain Security** — TLSv1.3 · HSTS · DNSSEC · DMARC

## Plans (1)

- **Sunset Header Plans Pricing**

## Tags

API Deprecation, HTTP Headers, RFC 8594, RFC 9745, API Lifecycle, REST APIs, Standards

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Profiled by [API Evangelist](https://apievangelist.com) and published on [APIs.io](https://apis.io/providers/sunset-header/). Scores are computed from the provider's own public artifacts under a published rubric.