MCPJam

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**MCPJam** is the open-source **testing & evaluations platform for MCP server developers** who ship. Interactively test tools, prompts, resources, and authorization across 16 client configurations and 170+ models. Run evals on test cases, get insights on what's breaking, and gate regressions to secure every deployment. # 🚀 Quick start Open the hosted app. No install needed. 👉 **[app.mcpjam.com](https://app.mcpjam.com)** ... or run MCPJam locally for HTTP/S and local STDIO servers: ```bash npx @mcpjam/inspector@latest ``` # 👋🏽 Why MCPJam Clients like ChatGPT, Claude, and Cursor all read your server differently. MCPJam catches those differences, shows where your server breaks, and tells you how to fix it: - **Inspect & debug**: Explore your server's tools, resources, and prompts in one place. Test prompts from real LLMs, with full visibility & traces on every JSON-RPC message and OAuth exchange. - **Cross-client evals**: Score agent behavior across 16 client configurations — ChatGPT, Claude, Cursor, Copilot, and more — to understand how your MCP integrations perform across all users. Track accuracy, latency, and tool-call performance over time. - **Security & reliability**: Automate conformance & behavior checks in CI/CD to catch regressions before they reach production. MCPJam Playground trace view: every tool call, agent step, and JSON-RPC message in one timeline

_Trace view: every tool call, agent step, and JSON-RPC message in one timeline._

# 🔨 Features | Capability | What it does | | -------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | **Playground** | Cross-client chat interface that emulates UIs, tool calls, and skills (with full traces). OpenAI Apps SDK and MCP app UIs, text tools, and a Chrome DevTools-style widget emulator. [Read more](https://docs.mcpjam.com/inspector/playground) | | **OAuth Debugger** | Visualize your OAuth & EMA requests step-by-step to find the source of errors. Guided MCP OAuth conformance checks across protocol versions 03-26, 06-18, 11-25, and 2026-07-28; DCR, client pre-registration, and CIMD. [Read more](https://docs.mcpjam.com/inspector/guided-oauth) | | **Server Debugging** | Manually run tools, resources, templates, prompts, and elicitation flows with full JSON-RPC logs. | | **Skills** | Extend models with reusable behaviors in Playground. Local skills are read from your filesystem and never leave your machine; a project can also carry hosted skills, available on accounts where that is enabled. [Read more](https://docs.mcpjam.com/inspector/skills) | | **Workspaces** | Shared server groups with real-time team sync, so everyone tests the same config. [Read more](https://docs.mcpjam.com/inspector/workspaces) | | **Evals** | Test cases with expected tool calls, run across LLMs, with accuracy metrics over time. [Read more](https://docs.mcpjam.com/inspector/test-cases) | | **CLI** | Probe servers, run doctor checks, exercise OAuth, and list tools/resources/prompts from your terminal. [Read more](https://docs.mcpjam.com/cli/overview) | | **SDK** | Programmatically drive inspections, snapshot capabilities, and assert on tool/resource shapes from your own tests. [Read more](https://docs.mcpjam.com/sdk) | | **CI/CD** | Run conformance, E2E tests, evals, and OAuth checks on every PR in GitHub Actions or any pipeline. [Read more](https://docs.mcpjam.com/cli/ci) | --- ## Playground Debug your server against a model using tool calls or in-panel chat, with Chat, Trace, and Raw views. Supports the OpenAI Apps SDK and MCP app UIs, text tools, and a Chrome DevTools-style widget emulator so you can iterate on widgets locally. - Invoke a tool to render its widget instantly, or drive your server with an LLM. - Watch all JSON-RPC and `window.openai` messages in the logs. - Switch the emulator between Desktop, Tablet, and Mobile. - Test locale changes, CSP permissions, light/dark mode, hover & touch, and safe-area insets. MCPJam comparing frontier models side by side

MCPJam comparing frontier models side by side

## OAuth Debugger Guided MCP OAuth conformance checks with step-by-step explanations. Test against every version of the OAuth spec (2025-03-26, 2025-06-18, 2025-11-25, and the 2026-07-28 draft), with support for client pre-registration, Dynamic Client Registration (DCR), and Client ID Metadata Documents (CIMD). MCPJam OAuth flow debugger

## Server Debugging Everything you need to test an MCP server by hand: run tools, resources, resource templates, prompts, and elicitation flows with full JSON-RPC observability. Every feature of the original inspector, and more. MCPJam MCP server debugging view

## Skills Use Skills in Playground to extend models with reusable behaviors. Local skills are read from your filesystem and never leave your machine; a project can also carry hosted skills, available on accounts where that is enabled. [Read more](https://docs.mcpjam.com/inspector/skills) ## Workspaces Group servers into shared workspaces with real-time team sync, so everyone on your team tests against the same configuration. [Read more](https://docs.mcpjam.com/inspector/workspaces) ## Evals Define test cases with expected tool calls and run them across multiple LLMs. Track accuracy over time to catch regressions early and improve your server with every iteration. [Read more](https://docs.mcpjam.com/inspector/test-cases) ## CLI Run MCPJam from the terminal for fast local dev loops and CI. Probe servers, run OAuth checks, inspect tools and resources, and execute evals without leaving your shell. [Read more](https://docs.mcpjam.com/cli/overview) ## SDK Programmatic access to MCPJam for custom tooling, scripting, and integrations. Build your own workflows on top of MCPJam's inspection and evaluation primitives. [Read more](https://docs.mcpjam.com/sdk) ## CI/CD Wire MCPJam into GitHub Actions, GitLab CI, or any CI system to run conformance, E2E tests, and evals on every PR — and catch MCP server regressions before they ship. [Read more](https://docs.mcpjam.com/cli/ci) # 🔌 Install MCPJam Inspector runs three ways: a hosted web app, a desktop app for Mac and Windows, or via your terminal. The web app is HTTPS-only and has no install. Terminal and Desktop support HTTP/S and local STDIO servers. [![Node.js](https://img.shields.io/badge/Node.js-20+-green.svg?style=for-the-badge&logo=node.js)](https://nodejs.org/) [![TypeScript](https://img.shields.io/badge/TypeScript-5+-blue.svg?style=for-the-badge&logo=typescript)](https://www.typescriptlang.org/) > Node.js 20+ is only required for the terminal install (`npx`). The hosted and desktop apps have no local runtime requirements. **Hosted web app**: Open [app.mcpjam.com](https://app.mcpjam.com). No install, always latest, and you can share server links with teammates like a Google Doc. HTTPS server URLs only; no STDIO, tunneling, skills, or tasks (those need the local inspector). [Hosted docs](https://docs.mcpjam.com/hosted/overview) **Desktop app**: Download the installer. Supports HTTP/S and local STDIO, no Node.js required. [Install Mac](https://github.com/MCPJam/inspector/releases/latest/download/MCPJam.Inspector.dmg) · [Install Windows](https://github.com/MCPJam/inspector/releases/latest/download/MCPJam-Inspector-Setup.exe) **Terminal**: Supports HTTP/S and local STDIO. Open the printed `localhost` URL after it starts. ```bash npx @mcpjam/inspector@latest ``` **Docker**: There is no published image, so build one from source first. Bound to localhost for security. Available at `http://127.0.0.1:6274`. Always use `-p 127.0.0.1:6274:6274` (not `-p 6274:6274`) to keep the inspector local-only. On macOS/Windows, reach host MCP servers via `http://host.docker.internal:PORT`. ```bash git clone https://github.com/MCPJam/inspector.git cd inspector docker build -t mcpjam/mcp-inspector:local -f mcpjam-inspector/Dockerfile . docker run -p 127.0.0.1:6274:6274 mcpjam/mcp-inspector:local ``` # 👨‍💻 Contributing We're grateful you're considering it. Read the [contributing guide](CONTRIBUTING.md) to get started, and come say hi in [Discord](https://discord.gg/JEnDtz8X6z). # 🌍 Community & links [Website](https://www.mcpjam.com/) · [Blog](https://www.mcpjam.com/blog) · [Pricing](https://www.mcpjam.com/pricing) · [Docs](https://docs.mcpjam.com/) · [Discord](https://discord.gg/JEnDtz8X6z) · [𝕏 (Twitter)](https://x.com/mcpjams) · [LinkedIn](https://www.linkedin.com/company/mcpjam) # 📄 License Licensed under the **Apache License 2.0**. See [LICENSE](LICENSE).