What is Mcpproxy Stdio To Sse

MCPProxy-STDIO-to-SSE is a lightweight .NET console bridge that enables STDIO-based clients to communicate with an SSE-backed MCP server. It establishes a long-lived SSE connection and facilitates bidirectional data transfer between STDIN and the server.

Use cases

Use cases include integrating legacy applications with modern SSE-based services, developing real-time data processing tools, and enabling interactive command-line interfaces that communicate with MCP servers.

How to use

To use MCPProxy-STDIO-to-SSE, clone the repository, build the project using .NET 6.0 SDK or later, and run the application with the required URL. You can optionally include additional HTTP headers for authentication.

Key features

Key features include a bidirectional bridge for data transfer, automatic session discovery, structured logging with timestamps, and configurable headers for both SSE subscriptions and POST requests.

Where to use

MCPProxy-STDIO-to-SSE is suitable for applications that require real-time communication between STDIO-based clients and MCP servers, such as desktop applications and web services that utilize server-sent events.

MCPProxy-STDIO-to-SSE

Makes a MCP SSE server compatiable with WindSurf and Claude Desktop

MCPProxy-STDIO-to-SSE
A lightweight .NET console bridge that lets any STDIO-based client speak to an SSE-backed MCP server.
It:

Opens a single long-lived SSE connection to BASE_URL/sse, discovers the /message?sessionId=… endpoint.

Forwards every JSON-RPC line read from STDIN as an HTTP POST to BASE_URL/message?sessionId=….

Streams each SSE data: payload (other than the endpoint event) to STDOUT.

Logs every message sent and received (with timestamps and pretty-printed JSON) to MCPProxy-STDIO.log in your temp directory.

Features
Bidirectional bridge: STDIN→HTTP POST and SSE→STDOUT.

Automatic session discovery via the event: endpoint frame.

Structured logging (timestamps, “Sent”/“Received” markers, indented JSON).

Configurable headers on both SSE subscribe and POST requests.

Prerequisites
.NET 6.0 SDK or later

An MCP-compatible server exposing:

GET /sse (SSE stream with an event: endpoint frame)

POST /message?sessionId={id} (accepts JSON-RPC payloads)

Building

git clone https://github.com/yourorg/MCPProxy-STDIO-to-SSE.git
cd MCPProxy-STDIO-to-SSE
dotnet build -c Release

Usage

# Basic (no extra headers):
dotnet run --project src/Program.cs http://localhost:3001

# With additional HTTP headers:
dotnet run --project src/Program.cs http://localhost:3001 ApiKey 12345

Once launched, the app will:
Open GET http://localhost:3001/sse with Accept: text/event-stream.
Wait for an event: endpoint frame—e.g.:

event: endpoint
data: /message?sessionId=Wp6wxiY6PyBRoTtCNyLucw

Read lines from your STDIN and POST each one as JSON to:

POST http://localhost:3001/message?sessionId=Wp6wxiY6PyBRoTtCNyLucw
Content-Type: application/json

{"jsonrpc":"2.0","id":1, ...}

Print every other SSE data: payload to STDOUT, for example:

{"jsonrpc":"2.0","id":1,"result":{"protocolVersion":"2024-11-05", ...}}

Write a detailed log of “Sent” and “Received” messages (with timestamps and formatted JSON) into:

%TEMP%\MCPProxy-STDIO.log

Use this bridge to connect any STDIO-driven LSP/JSON-RPC client (including Claude Desktop) to a web-based SSE/MCP backend seamlessly.
Sample Claude JSON configuration

{
  "mcpServers": {
    "Local CNET Debug": {
      "command": "C:\\Users\\User\\source\\repos\\MCPProxy-STDIO-to-SSE\\MCPProxy-STDIO-to-SSE\\bin\\Debug\\net6.0\\MCPProxy-STDIO-to-SSE.exe",
      "args": ["http://localhost:4858/McpHandler.ashx/sse"],
      "env": {
        "BRAVE_API_KEY": "your-api-key"
      }
    }
  }
}