Local Inspector for ChatGPT Apps SDK & MCP Apps

Test and develop ChatGPT apps and MCP apps (ext-apps) locally. MCPJam is the fastest way to iterate on your apps. No more ngrok or ChatGPT subscription needed.

Run in terminal:

npx@mcpjam/inspector@latest

Or download the desktop app

macOS Windows

ChatGPT Apps Builder

Like Chrome DevTools for ChatGPT Apps. Emulator that exposes all windows.openai API calls and JSON-RPC traffic, fully simulating ChatGPT's behavior.

OAuth debugger

Visualize and debug MCP authorization flows. Verify that your OAuth implementation conforms to the MCP spec at every step.

Read the guide

LLM playground

1:1 emulation with ChatGPT. Test your ChatGPT App against different models in the LLM playground. We provide frontier models such as GPT-5 for free. View in different display modes.

Contact us

We are happy to help with your MCP strategy. Tell us about what you're building and we'll get in touch with you.

or email us at [email protected]