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Testing and Debugging WebSockets

Last updated: 27 September 2026

A WebSocket connection starts as an HTTP request that asks to upgrade protocols. A page loading successfully tells you very little about whether that upgrade works.

Check the handshake first

In the Network tab, find the WebSocket request. Look at the URL, response status, and upgrade headers. If a reverse proxy sits in between, confirm it forwards the upgrade correctly and sends the request to the service that expects it.

Then inspect messages

A successful connection can still exchange the wrong data. Check the message format and whether the server closes the connection with a code or reason. Avoid pasting authentication-bearing WebSocket URLs into public tools: query strings can end up in logs and history.

  • WebSocket Frame Parser — Decode a raw WebSocket frame from hex and explain its opcode, length and payload.
  • WebSocket Tester — Open a WebSocket from the page, send frames and watch what the server sends back.