WebSocket Inspector

About this tool

This connects directly from your browser to any WebSocket server you give it — nothing passes through this site's own infrastructure, because there isn't any involved beyond serving this page. The connection, every message you send, and every message you receive all happen client-side between your browser and that server.

It's useful for poking at your own WebSocket APIs during development: quickly checking a connection opens, sending test frames by hand, and watching the raw traffic go by with timestamps, without needing a separate desktop client.