Internet-Draft Abbreviated Title May 2023
Smith Expires 5 November 2023 [Page]
Internet Engineering Task Force
Intended Status:
Standards Track
K. Smith, Ed.

api-catalog: A well-known URI to help discovery of APIs


This document defines the "api-catalog" well-known URI. It is intended to facilitate discovery of the APIs published by a Web host.

Status of This Memo

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This Internet-Draft will expire on 5 November 2023.

Table of Contents

1. Introduction

A Web host may publish Application Programming Interfaces (APIs) to encourage requests for interaction from external parties. Such APIs must be discovered before they may be used - i.e., the external party needs to know what APIs a given Web host exposes, including their purpose, any constraints to use, and the endpoints to interact with the APIs. To faciliate discovery of this information, this document proposes a well-known URI, 'api-catalog', as a location where a Web host's API endpoints are listed and described.

1.1. Goals and non-goals

The primary goal is to facilitate the discovery of both a Web Host's public API endpoints, and metadata that informs the potential API client of the purpose of each API and any constraints around usage.

Non-goals: this document does not mandate paths for API endpoints. i.e., it is not mandating that my_example_api should be available at (although it is not forbidden to do so).

1.2. Requirements Language

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] when, and only when, they appear in all capitals, as shown here.

2. Using the 'api-catalog' well-known URI

The api-catalog well-known URI is intended for HTTP(S) servers that publish APIs and wish to facilitate their discovery. The api-catalog URI SHALL follow the path-prefix for "well-known locations" defined in [RFC8615], namely /.well-known/ : i.e.,

A Web host ( supporting this URI SHALL resolve an HTTP(S) GET request to /.well-known/api-catalog with a list of public APIs. Web hosts SHOULD utilise existing formats to list their APIs, for example [apisJson] or [HAL].

3. IANA Considerations

This specification registers the "host-meta" well-known URI in the Well-Known URI Registry as defined by [RFC6415].

URI suffix: api-catalog

Specification document(s): draft-smith-api-catalog-00

Related information: The "api-catalog" documents obtained from the same host using the HTTP and HTTPS protocols (using default ports) MUST be identical.

4. Security Considerations


5. References

5.1. Normative References

Nottingham, M., "Well-Known Uniform Resource Identifiers (URIs)", RFC 8615, DOI 10.17487/RFC8615, , <>.
Hammer-Lahav, E., Ed. and B. Cook, "Web Host Metadata", RFC 6415, DOI 10.17487/RFC6415, , <>.

5.2. Informative References

Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <>.
Kelly, M., "JSON Hypertext Application Language", , <>.
apis-json, "APIs.json: an API discovery definition format", , <>.

Appendix A. Appendix 1

TODO, add examples in HAL and apisJson



Author's Address

Kevin Smith (editor)
One Kingdom Street
W2 6BY
United Kingdom