---
title: "API catalog (RFC 9727) defined | Agent Ready Checklist"
description: "API catalog (RFC 9727): A linkset document at /.well-known/api-catalog listing a publisher's APIs with links to their OpenAPI files and docs."
canonical: https://agentreadychecklist.com/glossary/api-catalog
site: "Agent Ready Checklist"
last_updated: 2026-11-05
section: "Glossary"
---

# API catalog (RFC 9727) defined | Agent Ready Checklist

> API catalog (RFC 9727): A linkset document at /.well-known/api-catalog listing a publisher's APIs with links to their OpenAPI files and docs.

Source: https://agentreadychecklist.com/glossary/api-catalog
Site: Agent Ready Checklist
Last reviewed: 2026-11-05
Agent endpoints: https://agentreadychecklist.com/llms.txt (index), https://agentreadychecklist.com/openapi.json (API), https://agentreadychecklist.com/mcp (MCP server), https://agentreadychecklist.com/ask (search)
Access: https://agentreadychecklist.com/auth.md (no key). Pricing: https://agentreadychecklist.com/pricing.md (free).

# API catalog (RFC 9727)

A linkset document at /.well-known/api-catalog listing a publisher's APIs with links to their OpenAPI files and docs. Example: {"linkset":\[{"anchor":"https://api.example.com/v1","service-desc":\[{"href":"https://api.example.com/openapi.json"}\]}\]}. Cloudflare Radar found MCP Server Cards and API Catalogs together on fewer than 15 sites of its scanned set. The FAQ asks: What is the difference between the AI Catalog and the API catalog?

## Definition

A linkset document at /.well-known/api-catalog listing a publisher's APIs with links to their OpenAPI files and docs.

## Example

```json
{"linkset":[{"anchor":"https://api.example.com/v1","service-desc":[{"href":"https://api.example.com/openapi.json"}]}]}
```

## Nearby terms

-   [.well-known](https://agentreadychecklist.com/glossary/well-known/)URI prefix defined in RFC 8615 for site-wide metadata at fixed paths.
-   [OpenAPI](https://agentreadychecklist.com/glossary/openapi/)Machine-readable contract for an HTTP API: paths, parameters, responses, auth.

## Asked about it

### What is the difference between the AI Catalog and the API catalog?

The AI Catalog (AR-FIND-04) at /.well-known/ai-catalog.json lists every agent resource, MCP cards and skills included. The API catalog (RFC 9727) at /.well-known/api-catalog lists APIs with links to OpenAPI and docs.

## Sources

-   [isitagentready.com/.well-known/agent-skills/api-catalog/SKILL.md](https://isitagentready.com/.well-known/agent-skills/api-catalog/SKILL.md)read 2026-11-04
-   [blog.cloudflare.com/agent-readiness/](https://blog.cloudflare.com/agent-readiness/)read 2026-11-04
-   [isitagentready.com/.well-known/agent-skills/ard/SKILL.md](https://isitagentready.com/.well-known/agent-skills/ard/SKILL.md)read 2026-11-04

Last reviewed 2026-11-05. AgentReady v2.0, read 2026-11-04.