Building a WebSocket Debugging CLI with Node.js

WebSockets power the real-time web — chat apps, live dashboards, multiplayer games, collaborative editors. But when something goes wrong with a WebSocket connection, debugging it is surprisingly painful. In this tutorial, we will build a full-featured WebSocket debugging CLI from scratch. By the end, you will have a tool that connects to any WebSocket endpoint, logs messages with timestamps, filters by pattern, measures latency, records sessions for replay, and supports multiple concurrent connections — all from your terminal. Why Browser DevTools Fall Short If you have ever tried to debug WebSocket traffic in Chrome DevTools, you know the frustration: No filtering : You cannot filter messages by content or pattern. No replay : You cannot resend a previous message without writing code. No recording : Once you close the tab, your message history is gone. No scripting : No way to automate sends or set up timed pings. No multi-connection view : You have to switch between connections manua