The world's largest API knowledge base, built for agents.
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API documentation is scattered across hundreds of sites, buried in PDFs, locked behind developer portals, and constantly going stale. AI agents are left to guess at parameters, hallucinate auth flows, and fail silently on edge cases.
One Knowledge fixes this. We've built structured, human-verified knowledge for every tool across 1,000+ platforms and we're opening all of it. 130,000+ tools, every parameter, every auth flow, every edge case. Structured for machines. Verified by humans, and tested before an agent runs it. Open source, so one fix reaches every agent. Free forever.
Get the knowledge into your agent in one of two ways. Both are free.
Remote MCP. Point any MCP-compatible agent at One's hosted server and sign in when it asks:
claude mcp add --transport http one https://mcp.withone.ai/mcpSetup guides for Cursor, Codex, Windsurf and other agents are at withone.ai/mcp.
The One CLI. For agents that can run a command line:
npm install -g @withone/cli
one initThe CLI will prompt you for your API key (get one free from the One Dashboard) and configure everything for your environment: Claude Code, Cursor, Claude Desktop, Windsurf, or any MCP-compatible agent.
Once connected, your agent finds the actions a task needs, with their knowledge, in one call (find_one_actions over MCP, one actions find in the CLI), then executes them across all 1,000+ platforms.
Access knowledge programmatically with the open API. All you need is a free One API Key.
All requests require the x-one-secret header:
x-one-secret: YOUR_ONE_API_KEY
| Endpoint | Description |
|---|---|
GET /open/knowledge/:platform |
Get a platform's overview |
GET /open/knowledge/:platform/auth |
Get a platform's authentication details |
GET /open/knowledge/:platform/actions |
List a platform's actions. Paginate with page (from 1) and limit (default 20, max 150) |
GET /open/knowledge/:platform/actions/search?query= |
Search a platform's actions, with an optional limit |
GET /open/knowledge/:platform/actions/:actionId |
Get an action's full knowledge |
GET /open/count/platforms, GET /open/count/tools |
Live counts, as shields.io badge JSON. No key needed |
Base URL: https://api.withone.ai
Knowledge comes back as Markdown with YAML front matter, in a markdown field. Action lists come back as { rows, total, pages, page }, each row with the action's id, title, method and path; search returns the matching rows.
# Example: Get Airtable's knowledge
curl 'https://api.withone.ai/open/knowledge/airtable' \
--header 'x-one-secret: YOUR_ONE_API_KEY'
# Example: List Airtable's first 50 actions, then read one by its id
curl 'https://api.withone.ai/open/knowledge/airtable/actions?limit=50' \
--header 'x-one-secret: YOUR_ONE_API_KEY'
curl 'https://api.withone.ai/open/knowledge/airtable/actions/ACTION_ID' \
--header 'x-one-secret: YOUR_ONE_API_KEY'For full API documentation, examples, and response schemas, see the docs.
Every piece of knowledge is structured, complete, and ready for machine consumption:
| Component | Description |
|---|---|
| Metadata | YAML front matter: platform name, category, version, image, URL, license, maintainer, last updated date |
| Authentication | OAuth details, required credentials, scopes, token refresh details |
| Actions | Every available API action with its prerequisites, method, URL, headers and description |
| Parameters | Required and optional path, query and body parameters, with types and descriptions |
| Enforcement Rules | Constraints that ensure correct API usage (e.g., query params vs body), with valid and invalid examples |
| Response Schemas | Full response structures for each outcome, with field types and descriptions |
| Examples | A sample request and worked usage examples for every action |
| Behavior & Notes | What the call does step by step, and its limits and caveats (time windows, expiring URLs, deprecations) |
The knowledge is maintained by One Systems Inc. and verified by humans. If you find something outdated, incorrect, or missing, open an issue and we'll fix it.
- Report outdated or incorrect knowledge - an action's parameters changed, auth flow updated, endpoint deprecated, etc.
- Request a new platform - a platform you'd like to see added to the knowledge base.
This project is licensed under the One Knowledge Commons License v1.0 (OKCL-1.0).
The knowledge is free to use, modify, and distribute with attribution. See the full license for details on metadata integrity, AI training usage, and community contributions.