0-suite /
web0

WebSocket Tester

connects only to the WebSocket endpoint you enter. Nothing else is contacted.

idle
frames

WebSocket connections aren't subject to the same-origin / CORS restrictions that block arbitrary cross-origin fetch reads, so this tester works fully in the browser: it connects directly to whatever ws:// or wss:// endpoint you give it.

Close codes worth knowing: 1000 normal, 1006 abnormal (no close frame, often a network drop or TLS/handshake failure), 1011 server error. Try wss://echo.websocket.events to see your messages echoed back.