MCP Proxy Server

What is MCP Proxy Server?

MCP Proxy Server is a central hub for Model Context Protocol (MCP) resource servers. It connects to multiple backend MCP servers (Stdio and SSE types), aggregates their tools and resources, and exposes them through a single unified SSE interface or as a Stdio MCP server. It handles routing, manages authentication, and optionally provides a Web Admin UI for configuration and monitoring.

How to use MCP Proxy Server?

Configure backend servers in config/mcp_server.json and optionally override tool properties in config/tool_config.json. Set environment variables (PORT, MCP_PROXY_SSE_ALLOWED_KEYS, ENABLE_ADMIN_UI, etc.). Run the server in development mode with npm run dev (Stdio) or npm run dev:sse (SSE). For production, use the Docker image from GHCR. Access the Admin UI at the server’s URL (if enabled) to manage servers and tools live.

Key features of MCP Proxy Server

• 🌐 Web UI for managing all connected MCP servers
• 🔧 Granular tool enable/disable and display name/description overrides
• 🔒 Dual SSE authentication (Bearer token or X-API-Key)
• 🔄 Robust session handling with client reconnection support
• ✨ Real-time Stdio install output streamed to the Admin UI
• 🖥️ Integrated web terminal for direct server interaction (opt‑in)

Use cases of MCP Proxy Server

• Aggregate multiple MCP servers into a single endpoint for client applications
• Manage tool availability and rename tools without modifying backend servers
• Securely expose MCP resources to multiple SSE clients with API key authentication
• Enable non‑technical users to install and configure Stdio MCP servers via a browser interface
• Monitor and debug server installation and operation through live logs and a web terminal

FAQ from MCP Proxy Server

What is MCP Proxy Server and how is it different from a regular MCP server?

MCP Proxy Server acts as a gateway that connects to one or more backend MCP servers (Stdio or SSE) and exposes their combined tools and resources. Unlike a single MCP server, it provides centralized configuration, tool filtering, and an optional web management interface.

How do I run MCP Proxy Server in SSE mode?

Run npm run dev:sse (development) or use the Docker image which runs in SSE mode by default. Ensure the PORT environment variable (default 3663) is set. Enable the Admin UI with ENABLE_ADMIN_UI=true and set ADMIN_USERNAME/ADMIN_PASSWORD.

How do I secure the SSE endpoint?

Set the MCP_PROXY_SSE_ALLOWED_KEYS environment variable with a comma‑separated list of keys. Clients must provide a key via the X-Api-Key header or ?key= query parameter. If not set, authentication is disabled.

Can I enable or disable specific tools without restarting the proxy?

Yes. Use the Web Admin UI to toggle tools on/off or modify their display names and descriptions. Changes are applied via a live configuration reload without restarting the proxy process.

What dependencies does MCP Proxy Server require?

Node.js (for npm install and build) or Docker for containerized deployment. Backend MCP servers are defined in config/mcp_server.json and can be Stdio executables or SSE endpoints. The Admin UI requires a browser and the ENABLE_ADMIN_UI=true environment variable.