WebSocket Debugger

How to use the WebSocket Debugger

This tool turns your browser into a full WebSocket client for testing, inspecting and diagnosing any ws:// or wss:// endpoint. Everything runs locally in your browser — no data is sent to us.

1. Create a connection tab

Click + New tab to open a new session. Each tab is fully independent, so you can run several WebSocket conversations side by side without interfering with each other.

2. Configure and connect

• URL — enter a ws:// or wss:// address. On a page served over HTTPS you can only reach wss:// endpoints, and the server certificate must be valid.
• Subprotocols — optional. Enter several names separated by commas (e.g. chat, superchat). After connecting, the tool shows which subprotocol the server actually selected.
• Timeout — how long to wait for the handshake before giving up, in case the server never answers.
• Preset — choose Native WS for a plain WebSocket, or Socket.IO v3-v4 to automatically append the Engine.IO handshake parameters (EIO version, transport=websocket, etc.).

Click Connect. The status badge moves through CONNECTING → OPEN → CLOSING → CLOSED, and every handshake step is logged.

3. Send frames

• Send text frames by typing into the Send box, or binary frames by choosing HEX, Base64 or JSON ArrayBuffer input.
• HEX input accepts space-separated bytes, e.g. 48 69 00 FF.
• JSON replies are auto-formatted, syntax-highlighted and collapsed into a tree for easy reading.
• Send templates support variables: {{ts}} (unix timestamp), {{time}} (HH:MM:SS) and {{rand}} (random 8-char string) are replaced at send time.

4. Automation

• Heartbeat — send an application-layer ping on an interval. This uses exponential back-off: if the server stops responding, the interval increases, and the message is retried up to the configured maximum before disconnecting. Manual disconnects are never auto-reconnected.
• Auto-reconnect — reconnect with exponential back-off plus jitter, up to a maximum number of retries.
• Loop send — repeat the current frame at a fixed interval (useful for stress or simulation).

5. Diagnostics

• Watch the raw handshake log, the negotiated subprotocol and extensions (such as permessage-deflate).
• Close codes are decoded: 1000–1015 map to their standard meaning, and 4000–4999 are flagged as application codes — check the server documentation for those.
• Every received/sent frame is logged with direction, byte count, timestamp and frame type.

6. Filter and export

• Filter logs by keyword, or by direction (RX / TX). Logs are capped at 5000 entries to keep the page responsive.
• Export the whole session as JSON, or copy the raw frame text.

Browser limitations to know

• You cannot set arbitrary HTTP request headers — only the subprotocol list is configurable.
• The browser controls protocol-level ping/pong automatically; you cannot send them yourself. Heartbeats here are application-layer text frames such as {"type":"ping"}.
• wss:// connections require a valid TLS certificate on the server.