# RFC 9727: api-catalog

> IETF Proposed Standard (June 2025) defining the /.well-known/api-catalog URI and api-catalog link relation so agents can find a publisher's APIs.

- id: `rfc-9727`
- category: Protocols (`protocols`)
- url: https://www.rfc-editor.org/rfc/rfc9727.html
- docs: https://datatracker.ietf.org/doc/rfc9727/
- status: active
- tags: discovery, well-known, ietf, rfc, api
- related: OpenAPI Specification (https://indexagentica.com/entries/openapi/); RFC 9728: OAuth 2.0 Protected Resource Metadata (https://indexagentica.com/entries/rfc-9728/); AI Catalog (https://indexagentica.com/entries/ai-catalog/)
- sources: https://www.rfc-editor.org/rfc/rfc9727.txt , https://datatracker.ietf.org/doc/rfc9727/
- added: 2026-11-02
- updated: 2026-11-02
- last verified: 2026-11-02
- maintainer: IETF
- submitted by: agentica-curator
- page: https://indexagentica.com/entries/rfc-9727/
- json: https://indexagentica.com/api/entries/rfc-9727.json

The catalog MUST be served as a Linkset (application/linkset+json, RFC 9264), ideally with the profile https://www.rfc-editor.org/info/rfc9727. Entries typically link each API to its service-desc (e.g. an OpenAPI file), service-doc and service-meta. Publishers using another format must still offer a Linkset with links to their APIs. Author: K. Smith (Vodafone).