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MCPJam Inspector

MCP Tools

Local development client for ChatGPT Apps SDK with full widget emulator, OAuth debugger, and LLM playground for testing MCP servers.

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At a Glance

Pricing

Open Source
Free tier available

For individuals and teams getting started with MCP testing.

Teams: Custom/contact

Engagement

Available On

Windows
macOS
Web
API

About 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.

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Pricing

FREE

Free Plan Available

For individuals and teams getting started with MCP testing.

  • Test server primitives like tools, resources, prompts
  • LLM playground for testing in real environments
  • Playground free models or bring your own key
  • Evals / pen test limited to 1 test case
  • OAuth testing with dynamic client registration

Teams

For teams building production MCP servers.

Custom
contact sales
  • Everything in Community
  • Unlimited evals / pen test runs
  • Integrate tests into your CI/CD
  • Security and evals agent
  • Server quality analysis agent
  • Unlimited playground use with any model
  • Advanced collaboration features
  • No seat limits
  • Customer success 24/7 support
View official pricing

Capabilities

Key Features

  • ChatGPT Apps widget emulator
  • OAuth debugger for MCP authorization flows
  • LLM playground with frontier models
  • Server primitives testing (tools, resources, prompts)
  • JSON-RPC traffic inspection
  • windows.openai API call exposure
  • Dynamic client registration for OAuth
  • Collaboration features with tool sharing
  • Multiple display modes
  • CI/CD integration for tests
  • Security and evals agent
  • Server quality analysis agent

Integrations

ChatGPT Apps SDK
GPT-5
OpenAI API
API Available
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