---
title: "Ellelion developer resources"
description: "Ellelion developer resources: OpenAPI, catalogs, auth.md."
canonical: "https://ellelion.com/developers"
last-updated: "2026-08-28"
---

# Ellelion developer resources

Machine-readable entry for Ellelion LLC. This origin publishes a read-only HTTP surface. It is not a key-issuing developer platform. There is no API-key product.

## When to use this origin

Use Ellelion when you need the public list of AI agents for developers and builders, the pricing/auth facts (no keys on this host), or the catalogs below. Do not treat ellelion.com as a write API or payment rail.

## Start here

- OpenAPI: https://ellelion.com/openapi.json (version 1; JSON under /api/v1/)
- RFC 9727 catalog: https://ellelion.com/.well-known/api-catalog
- ARD catalog: https://ellelion.com/.well-known/ai-catalog.json
- Agent skills: https://ellelion.com/.well-known/agent-skills/index.json
- RFC 9728 resource metadata: https://ellelion.com/.well-known/oauth-protected-resource
- auth.md: https://ellelion.com/auth.md
- WebMCP manifest: https://ellelion.com/.well-known/webmcp
- MCP (catalog): https://ellelion.com/.well-known/mcp
- MCP server card: https://ellelion.com/.well-known/mcp/server-card.json
- MCP (docs): https://ellelion.com/.well-known/mcp/docs
- Agent instructions: https://ellelion.com/.well-known/agent-instructions
- A2A card: https://ellelion.com/.well-known/agent-card.json
- NLWeb: https://ellelion.com/ask
- GitHub: https://github.com/ellelion/ellelion
- llms.txt: https://ellelion.com/llms.txt
- Pricing: https://ellelion.com/pricing
- Authentication: https://ellelion.com/authentication

## Versioning and deprecation

Breaking JSON changes increment the path (`/api/v2/`). Deprecated operations receive `Deprecation` and `Sunset` headers and a note in OpenAPI. None are deprecated today.

## Rate limits

Responses on `/api/*` include IETF `RateLimit` and `RateLimit-Policy` headers. Advertised budget: 120 requests per 60 seconds per client.

## Quickstart

No signup. Omit Authorization. Example request: GET https://ellelion.com/api/v1/catalog?limit=50. Also GET https://ellelion.com/openapi.json and GET https://ellelion.com/api/v1/sandbox/catalog.

## API keys

There are no API keys on ellelion.com. Public GETs require no credentials. Do not send an Authorization header.

## Documentation

HTML portal: https://ellelion.com/developers and https://ellelion.com/docs. Versioning: https://ellelion.com/versioning. Public repo: https://github.com/ellelion/ellelion.

## Sandbox

GET https://ellelion.com/api/v1/sandbox/catalog is the sandbox environment (public catalog, environment=sandbox).

## MCP

Product MCP: POST https://ellelion.com/mcp. Docs MCP: POST https://ellelion.com/mcp/docs. Discovery: https://ellelion.com/.well-known/mcp.json.

## What this host does not run

Hosted Streamable HTTP MCP is real: product catalog at /mcp and docs at /mcp/docs. There is no token-issuing OAuth authorization server, no webhook hub, and no official CLI for ellelion.com.