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1. Open MCPJam

Web: HTTPS only, runs in the browser with no install. Server links can be shared with teammates. Terminal and Desktop: HTTP/S and local STDIO.

Web App

HTTPS only. No install. Share with your team.

Terminal

npx @mcpjam/inspector@latest. HTTP/S and local STDIO.

Desktop App

Mac or Windows. HTTP/S and local STDIO.

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2. Draw something

On first launch, MCPJam connects the Excalidraw sample server (diagramming MCP app) and opens App Builder with this prompt: 
Draw me an MCP architecture diagram
Press Send. The diagram renders in the app. No API key, ngrok, or ChatGPT/Claude subscription needed. Sequence: tool call → widget → inspect.
Use the widget debug icons to open tool input/output, CSP activity, widget state, and JSON-RPC for that result.

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3. Connect your own server

Open Servers in the left sidebar. Click Add server.
  • HTTP: Paste a URL ending in /mcp. The web app accepts HTTPS URLs only. Desktop and Terminal accept HTTP or HTTPS. Add a bearer token or use the OAuth Debugger if the server requires auth.
  • STDIO (Desktop and Terminal only): Paste a command such as npx -y @modelcontextprotocol/server-everything. Not available in the web app. See Hosted App.
Each Connected server is available in App Builder, Chat, Tools, Prompts, and Resources. Connect more from Servers anytime.

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4. Where to go next

App Builder

Debug your MCP server against a model. Renders OpenAI Apps SDK and MCP app UIs as well as plain text tool results. Run individual tool calls, use the in-panel chat, or mix both, and switch between the Chat view, Trace, and Raw. When a tool returns a widget, use the emulator (iframe, window.openai, CSP, device frames, locale, widget debugging).

Chat

Host-style chat (like ChatGPT or Claude): enable one or more MCP servers, then switch between the Chat view, Trace, and Raw as you go. Compare up to 3 frontier models on the same prompt.

OAuth Debugger

Step through your MCP authorization flow and inspect each stage. Check conformance across protocol versions (03-26, 06-18, 11-25) and client registration paths: Dynamic Client Registration (DCR), client pre-registration, and CIMD.

Workspaces

Group servers; share configuration with your team