API Catalog (RFC 9727)

Discover api-catalog (RFC 9727, published June 2025) is an IANA-registered well-known URI (/.well-known/api-catalog) and HTTP link relation (rel="api-catalog") that returns an RFC 9264 application/linkset+json document listing a publisher's machine-readable APIs, OpenAPI specifications (service-desc), documentation (service-doc), and status endpoints (status). In the agentic web, RFC 9727 provides the standards-track IETF foundation for domain-level API discovery alongside /.well-known/ard.json. Used by: api-catalog-rfc9727, ard.