A developer tool for inspecting Model Context Protocol (MCP) servers. It ships as a single package, @modelcontextprotocol/inspector, that provides three ways to inspect a server:
- Web — a Vite + React + Mantine single-page app with a Node backend.
- CLI — a scriptable command-line client for automation, CI, and fast agent feedback loops.
- TUI — an interactive terminal UI built with Ink.
All three run through one global mcp-inspector binary:
npx @modelcontextprotocol/inspector # web UI (default)
npx @modelcontextprotocol/inspector --cli # CLI
npx @modelcontextprotocol/inspector --tui # TUIWarning
On a machine with no OS keychain, secrets are saved to a plaintext file by default. That covers Linux without libsecret or a Secret Service, headless and SSH sessions, Termux, and containers with a mounted volume. OAuth client secrets and stdio env: values then go to ~/.mcp-inspector/secrets.json, unencrypted unless you supply a key. See Where secrets are stored for how to get a keychain back, encrypt the file, or keep secrets in memory only.
Upgrading from v1? Read the v1 → v2 migration guide — CLI flags, the new
--configvs.--catalogsplit, the Node engine bump, and what no longer ships.
Repo status. This is the v2 line of the Inspector. Active development happens on
v2/main(the develop branch — all v2 PRs target it), which is merged intomainat milestone releases;mainis the default branch and holds the latest released v2, published to the npmlatesttag. The legacy v1 line lives onv1/main— security fixes only, published straight from that branch to the npmv1-latesttag (npx @modelcontextprotocol/inspector@v1-latest). SeeAGENTS.mdfor branch/board conventions.
Requires Node >=22.19.0.
npm install # at the repo root; postinstall cascades into every client
npm run build # web → cli → tui → launcherFor day-to-day web iteration, run Vite directly — fast HMR, no launcher build needed:
cd clients/web