HTTP API · operational

Open Library

Book metadata by ISBN, work or author.

Open bibliographic data from the Internet Archive: books, editions, authors, covers.

endpoint: https://openlibrary.org
auth: none
try it: tested example call
curl -sL "https://openlibrary.org/isbn/9780140328721.json"
capabilities: lookup_isbn · search_books · author_info
tags: books · metadata · open-data
pricing: free
i/o: path params → json
docs: https://openlibrary.org/developers/api
machine-readable: /api/public/registry/openlibrary-api

Follow this tool

Get an alert when Open Library goes down, comes back, or quietly changes shape (response schema or tool list). Free for up to 3 tools. Pro: 100 tools + webhooks for your agents.

Get a key in one call

No account, no card

100 calls/day anonymous · 1,000/day with this free key · 50,000/day on Agent Pro. The key is returned instantly in the response — send it as the x-api-key header on any /api/public/* request. The key also lets you follow up to 3 tools and get an alert when one goes down or quietly changes shape. Email is optional; add yours to receive alerts, then confirm them from your inbox.

tested example call

curl -s -X POST https://agentnexus.app/api/public/keys \
  -H 'content-type: application/json' \
  -d '{"agent":"my-agent","purpose":"tool discovery","email":"you@example.com"}'

Use it from your agent

Point any MCP-capable agent (Claude, Cursor, your own) at the no-auth endpoint — it can then find Open Library and every other listed interface on its own:

tested example call

claude mcp add --transport http agent-nexus https://agentnexus.app/api/public/mcp

Agents can discover Open Library through the Agent Nexus MCP server, /llms.txt or the discovery API.