Context7 is an open-source MCP server built by Upstash that feeds version-specific library documentation straight into coding agents like Cursor, Claude Code, and Windsurf. Instead of guessing against training data that went stale months ago, the agent pulls the real docs for the exact package version you have installed. If you write code against React 19 or Next.js 15 every day, this is the difference between code that compiles and code that fights you for an hour.
Core Features
- Resolves a library name to a Context7 ID and fetches docs for the specific version you name.
- Indexes more than 9,000 libraries and frameworks, from React and Vue to Prisma and Tailwind CSS.
- Works as a hosted remote endpoint or a self-hosted npm package called @upstash/context7-mcp.
- Ships two modes: an MCP server for any client, plus a ctx7 CLI skill that needs no server at all.
- Runs on Upstash edge infrastructure for low-latency doc retrieval inside the agent loop.
Use Cases
- Stop hallucinated APIs when building with fast-moving frameworks like Next.js or React.
- Keep a team's agents on the same documented version across a monorepo.
- Speed up onboarding to a new library without tab-switching to its documentation site.
Pricing
Context7 is free and MIT-licensed. You can run it with basic rate limits and no API key, or grab a free key from context7.com/dashboard for higher throughput. There is no paid tier for the core server.
Pros and Cons
- Pro: Free, MIT-licensed, and works with 30-plus MCP clients out of the box.
- Con: The hosted endpoint's parsing and crawl engine is proprietary, so fully air-gapped teams must self-host.
Our Take: Best for developers who live in Cursor or Claude Code and keep hitting outdated code examples; the only trade-off is that heavy self-hosters trade the hosted convenience for running the npm package themselves.
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