Chrome DevTools Network → WS

Filter to WS. Click a connection. Messages tab shows every frame in and out with timestamps.

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wscat CLI

wscat -c wss://example.com/ws -H "Authorization: Bearer $TOKEN"
> {"type": "ping"}
< {"type": "pong"}

Terminal-based WebSocket client. Send/receive raw frames. Testing without a browser.

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tcpdump for handshake

tcpdump -A -s0 'port 443' -w ws.pcap

Captures the raw handshake. Analyze in Wireshark. Great when TLS makes browsers hide details.