mcpplay

The FastAPI /docs experience, for MCP servers.

Documentation • Getting Started • Issues

⚡ Run your MCP server → instantly get an interactive UI.

https://github.com/user-attachments/assets/ecaa69d9-b441-44d8-b709-93b168398858

mcpplay gives you a browser-based playground for MCP-compliant servers. One command, and you get auto-generated forms, live results, and a full execution timeline.

Built for FastMCP workflows. Works with any MCP-compliant implementation.

Installation

pip install mcpplay
mcpplay demo

Your browser opens to http://localhost:8321. That's it!

mcpplay screenshot

Point it at your own server

mcpplay run server.py
mcpplay run --command "node server.js"
mcpplay run --command "uvx my-mcp-server"

Options

mcpplay run server.py --port 9000        # Custom port (default: 8321)
mcpplay run server.py --no-open          # Don't auto-open browser
mcpplay run server.py --no-reload        # Disable hot reload
mcpplay run server.py --env API_KEY=xxx  # Pass env vars to server

Features

Schema-aware forms - auto-generated from your tool's JSON Schema, with enums, nested objects, arrays, and defaults.
Live execution - run tools and see structured results instantly.
Persistent timeline - every call logged with inputs, outputs, and latency. Replay with one click.
Hot reload - edit your server, mcpplay restarts it. Session and timeline preserved.
Local-first - runs on localhost (127.0.0.1) with Origin validation. No remote exposure by default.

Comparison

| | mcpplay | MCP Inspector | MCPJam Inspector | |---|---|---|---| | Install | pip install | npx (Node required) | Docker | | Python native | ✅ | ❌ | ❌ | | Form generation | Full JSON Schema | Basic inputs | Basic inputs | | Hot reload | ✅ | ❌ | ❌ | | Execution timeline | Persistent, replayable | Log | Log |

Development

git clone https://github.com/gauthierpiarrette/mcpplay
cd mcpplay

# Python backend
uv sync --dev
uv run pytest

# Frontend (Svelte)
cd frontend
npm install
npm run dev      # Dev server with HMR
npm run build    # Build to src/mcpplay/static/

License

Apache 2.0

MCP Servers