Proxy MCP Server (Frank Fiegel)

HTTP and SSE streaming proxy for stdio-based MCP servers with multi-version support.

Data last scanned today · Reviewed today

48★ 285TypeScriptMIT

Overview

This TypeScript utility functions as a bridge, allowing MCP servers designed for stdio transport to be accessed via HTTP and SSE. By multiplexing downstream connections into a single upstream process, it enables flexible deployment configurations while maintaining compatibility across different protocol versions. The server manages protocol revisions ranging from 2024-10-07 through the 2026-07-28 standard. It intelligently handles request classification to ensure both legacy and modern clients can interact with the same endpoint without requiring individual configuration updates.

Our verdict

This tool carries a high-risk level with a security score of 48/100. The primary concern is that the authentication method remains unreviewed, posing a potential exposure risk for unauthorized access. Users should be aware that because it acts as a proxy, it currently lacks support for server-side prompts or sampling requests that require client input, limiting its use case to non-interactive tasks. It is best suited for experienced developers working in controlled, non-sensitive environments.

Supports concurrent 2025 and 2026-07-28 protocol revisions
Maintains a small footprint with only three direct dependencies
Includes active maintenance with commits as of two days ago
MIT licensed for open-source flexibility

Authentication mechanisms have not undergone security review
Cannot relay prompts, sampling, or roots requesting client input
Community-maintained software rather than an official vendor release
Multiplexing design results in specific upstream connection limitations

Setup

Claude Desktop

{
  "mcpServers": {
    "punkpeye-mcp-proxy": {
      "args": [
        "-y",
        "mcp-proxy"
      ],
      "command": "npx"
    }
  }
}

Paste into ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows), then restart Claude Desktop. Some servers require API keys or tokens as environment variables — check the project's README and add an "env" object if needed.

No read-only mode — running this grants full read/write access.
No built-in authentication — anyone with access to this config can invoke every tool it exposes.

Compatibility

Client	Local	Docker	Remote	Read-only
Claude Desktop
Cursor
VS Code
Windsurf
ChatGPT

Frequently asked questions

›Which MCP protocol revisions does the proxy support?

It serves protocol revision 2026-07-28 and the 2025-era revisions (2024-10-07 through 2025-11-25) from the same endpoint.

›How do I configure the proxy to front a 2026-07-28 MCP server?

You should use the --upstreamProtocol auto flag to ensure the proxy probes the server with server/discover first.

›Can the proxy handle requests that require client input like OAuth?

No, features requiring client input such as elicitation, sampling, and roots are currently not implemented due to the proxy's multiplexing design.

›Is it possible to manage logging levels upstream through the proxy?

No, logging levels are managed per downstream connection but are not forwarded upstream because the shared upstream connection carries only one global log level.

›How does the proxy handle client identity?

The upstream MCP server sees the proxy as its client rather than the individual downstream callers, which may affect telemetry tracking.

›Does the proxy support 2026-07-28 over stdio transport?

No, the stdio (startStdioServer) transport is currently limited to serving 2025-era clients only.