MCPJam Inspector

MCPJam Inspector is a local development client designed for building and testing ChatGPT Apps SDK applications. It provides a complete widget emulator that simulates ChatGPT's behavior, eliminating the need for ngrok or a ChatGPT subscription during development. The tool functions like Chrome DevTools for ChatGPT Apps, exposing all windows.openai API calls and JSON-RPC traffic.

• ChatGPT Apps Builder - Functions as a full emulator that exposes all API calls and JSON-RPC traffic, providing complete simulation of ChatGPT's behavior for local development and testing.

• OAuth Debugger - Visualizes and debugs MCP authorization flows, allowing developers to verify that OAuth implementations conform to the MCP specification at every step of the process.

• LLM Playground - Offers 1:1 emulation with ChatGPT, enabling testing of ChatGPT Apps against different models including frontier models like GPT-5 for free, with multiple display modes available.

• Server Primitives Testing - Supports testing of server primitives including tools, resources, and prompts for comprehensive MCP server validation.

• Collaboration Features - Includes team collaboration capabilities such as sharing tools and supporting up to 3 users per team on the free plan.

• Cross-Platform Availability - Available as both a CLI tool via npx and as downloadable desktop applications for macOS and Windows.

To get started, run npx @mcpjam/inspector@latest in your terminal or download the desktop app for your platform. The tool provides immediate access to test MCP servers locally without complex setup requirements.