inspector

MCPJam Inspector is a workbench for testing MCP servers, the plug-ins that give Claude, ChatGPT and Cursor access to your tools and data. Call tools by hand, watch every message go by, step through OAuth one stage at a time, and chat with your server through different models to see how each one uses it. It runs locally with one npx command or as a desktop app.

It goes well past modelcontextprotocol's official inspector: an emulator for ChatGPT app UIs, an OAuth debugger that tracks each spec version, and evals you can run in CI. The hosted web version only reaches HTTPS servers; local servers need the local app. Hosted chat runs on credits: Free gets 200 a day, Pro is $24/mo billed annually ($29 monthly) for 5,000 a month, Team is $199/mo annually ($249 monthly) for 50,000. Plug in your own model keys to spend your own tokens instead.

Anyone building an MCP server: the free local app is the fastest debugging loop around. Teams running evals in CI are who the paid plans are for.

The catch is the license label. The README and npm say Apache 2.0, but the eval services sit under a separate Enterprise license that needs a paid subscription for production use.