websocat

Connect to a WebSocket server

$ websocat ws://[example.com]/socket

$ websocat wss://[example.com]/socket

$ websocat -s [8080]

$ echo "hello" | websocat ws://[example.com]/socket

$ websocat -H "Authorization: Bearer [token]" wss://[example.com]/socket

$ websocat -b ws://[example.com]/socket

$ websocat -n ws://[example.com]/socket

$ websocat --binary tcp-l:127.0.0.1:[8080] ws://[example.com]/socket

websocat [options] address1 [address2]

websocat is a command-line WebSocket client and server, similar to netcat but for WebSocket connections. It enables bidirectional communication between various endpoints including WebSocket, TCP, Unix sockets, and stdio.
Basic usage connects stdin/stdout to a WebSocket URL. Input lines become WebSocket messages; received messages print to stdout. Use -b for binary data or -n for line-based text.
The server mode (-s) creates a simple WebSocket server useful for testing. For production, combine address specifiers like tcp-l: with ws:// for protocol conversion.
Address chaining enables complex setups like WebSocket tunnels, TCP-over-WebSocket, and command execution. The autoreconnect: wrapper handles connection drops automatically.
websocat supports both secure (wss://) and insecure (ws://) connections, custom headers for authentication, and ping/pong for connection keepalive.

-s, --server

Simple WebSocket server mode on specified port.

Send and receive binary frames instead of text.

Don't send close frame, disconnect abruptly.

Send one message and exit.

Only copy from address1 to address2.

Only copy from address2 to address1.

Add custom HTTP header.

Exit when stdin reaches EOF.

Force text frame mode.

Send WebSocket pings at interval.

Close connection if pong not received.

Accept invalid TLS certificates.

Set Origin header.

Suppress informational messages.

Increase verbosity level.

ws:// / wss://

WebSocket client connection.

TCP client/listener.

Unix socket client/listener.

Execute program and connect to its stdio.

Execute shell command.

Standard input/output.

Echo back received messages.

Wrapper for automatic reconnection.

Large messages may require increased buffer sizes. Some features require specific address type combinations. The --insecure flag should not be used in production. Complex address specifiers have steep learning curve.

websocat was created by Vitaly Shukela (vi) and first released around 2017. Written in Rust, it was designed as a Swiss Army knife for WebSocket operations. The tool has become popular for debugging WebSocket services, creating tunnels, and testing real-time applications. It continues active development with features for various networking scenarios.

nc(1), curl(1), socat(1), wscat(1)