MCP Proxy

A Stdio MCP server which proxies an SSE MCP server.

Overview

This proxy acts as a bridge between:

• An SSE-based MCP server endpoint
• Standard input/output for MCP client communication

It enables tools that use standard I/O for communication such as Claude Desktop (as of 2025-04-01) to interact with MCP implementations through an SSE interface.

Requirements

• JDK 21 or higher
• Gradle 8.0+ (Wrapper included)

Build Jar

./gradlew shadowJar

Testing

# Run all tests
./gradlew test

# Run a specific test
./gradlew test --tests "net.portswigger.TestName"