Context7

Context7 is a documentation service from Upstash that supplies AI coding agents with up-to-date, version-specific library documentation and code examples. It is designed to reduce a common problem with language models: generating code against outdated or non-existent APIs because their training data lags behind current library releases.

When an agent needs documentation, Context7 retrieves relevant docs and examples from the source and places them in the agent's context. Users can trigger it by adding a phrase such as "use context7" to a prompt, by naming a specific library ID (for example /supabase/supabase) to skip the library-matching step, or by mentioning a version so the matching documentation is used. A rule in tools such as Cursor or Claude Code can make it run automatically for library and API questions.

Context7 works in two modes. In MCP mode it registers a Context7 Model Context Protocol server so agents can call its documentation tools natively; the remote server URL is https://mcp.context7.com/mcp, with an API key passed in an Authorization header. In CLI plus skills mode it installs a skill that guides the agent to fetch docs with the ctx7 command-line tool, without MCP. The npx ctx7 setup command authenticates through OAuth, generates an API key and installs the chosen configuration, with options to target Cursor, Claude Code or OpenCode. The CLI requires Node.js 22.13 or newer, and npx ctx7 remove undoes the generated setup.

The project README recommends a free API key from the Context7 dashboard for higher rate limits; paid plans and current limits are listed on the official plans page. The client and MCP server code are published on GitHub by Upstash.

Because Context7 reads public documentation rather than a user's own systems, it is generally a lower-risk addition to an agent setup than servers that can modify code, data or infrastructure. Retrieved documentation should still be treated as untrusted input. Common uses include framework upgrades, working with unfamiliar SDKs and answering version-specific API questions.