Summary

A one-line fix for the transport mismatch, with the auth and CORS flags you need to actually deploy it.

The conversion itself is trivial to describe; what makes this usable beyond a demo is the surrounding flags — repeated headers and a bearer token for authenticated remotes, CORS by origin or regex, a health endpoint, and quiet logging. If you expose a stdio server on a port, those are the settings that decide whether it is safe.

What it is

A transport converter. Point it at a stdio MCP server and it serves that server over the network; point it at a remote SSE or Streamable HTTP server and it exposes it locally over stdio. Useful when the server you have and the client you want speak different transports.

What you get

Stdio to SSE: subscribe at `/sse`, post messages to `/message`, with `--port`, `--baseUrl`, `--ssePath` and `--messagePath` all configurable
Stdio to Streamable HTTP, stateless by default or `--stateful` with a `--sessionTimeout`, at `/mcp` by default
Stdio to WebSocket, exposing `ws://localhost:8000/message`
SSE to stdio and Streamable HTTP to stdio, for pulling a remote server into a command-line client
Authentication passed through: `--oauth2Bearer` adds an Authorization header, and `--header` can be repeated for anything else
Operational flags that matter when it is exposed: `--cors` allowing all origins or a list you supply including regex matching, `--healthEndpoint` for monitoring, and `--logLevel` set to debug, info or none

Requirements

Node, and `npx -y supergateway` with `--stdio`, `--sse` or `--streamableHttp` naming what to connect to. Nothing to install and no account. The package is `supergateway` 3.4.3.

Setup effort

One command — npx -y supergateway --stdio "uvx mcp-server-git"

Supergateway