joewalnes/websocketd

What is it?

Key features

• 01Wraps any program that reads STDIN and writes STDOUT as a WebSocket endpoint.
• 02Ships as a single executable for Linux, macOS and Windows with no external dependencies.
• 03Passes HTTP request details to scripts through CGI environment variables.
• 04Includes a static file server and a classic CGI server.
• 05Can listen on TCP or Unix domain sockets, and optionally forward STDERR.
• 06Provides a built-in developer console for sending and inspecting frames.

Use cases

• Prototyping a browser front end for an existing shell script or CLI tool.
• Streaming live system output such as logs or vmstat stats to a web dashboard.
• Building a quick browser-based REPL around a command-line interpreter.
• Testing WebSocket message handling in a script before writing a JavaScript client.

Quick start

1. 1

   Install on macOS with Homebrew

   brew install websocketd
2. 2

   Or download the single executable for your OS from the install page

3. 3

   Save a script such as count.sh and run it as a WebSocket server on port 8080

   websocketd --port=8080 ./count.sh

Things to know

• !Installing via Homebrew is only a one-line path on macOS; other systems need a manual download.

In collections

Topics

FAQ

What is websocketd?

A small CLI tool that wraps any STDIN/STDOUT program as a WebSocket server, like inetd for WebSockets. websocketd lets you expose an existing command-line program over WebSocket without writing any networking code. When a client connects, it starts the program, forwards each incoming message to the program's STDIN followed by a newline, and sends every line the program writes to STDOUT back to the client as a WebSocket message. When the connection closes, the process is shut down.

Is websocketd free to use? What license does it have?

websocketd is open source under the BSD-2-Clause license. Check the license terms before using it in commercial products.

Is websocketd still maintained?

Updated within 6 months. The last commit to websocketd was on Sep 7, 2026.

What can I use websocketd for?

Prototyping a browser front end for an existing shell script or CLI tool. Streaming live system output such as logs or vmstat stats to a web dashboard. Building a quick browser-based REPL around a command-line interpreter. Testing WebSocket message handling in a script before writing a JavaScript client.

How do I install websocketd?

Install on macOS with Homebrew: brew install websocketd Or download the single executable for your OS from the install page Save a script such as count.sh and run it as a WebSocket server on port 8080: websocketd --port=8080 ./count.sh

Where can I get websocketd?

The source code and installation instructions are on GitHub: https://github.com/joewalnes/websocketd