WebSocket Tester Guide
Open a WebSocket from the page, send frames and watch what the server sends back.
A short companion for WebSocket Tester: when it is useful, what it expects, and what to check before using the result.
What it does
Open a WebSocket from your browser, send text or binary frames, and watch everything that arrives in a timestamped log. The connection is made by the page itself, so it goes from your machine to the server you name and through nothing else. Binary frames can be typed as hex and are converted for you, and JSON that comes back is indented so it is readable. Close codes are explained rather than just printed.
Use the tool
Open WebSocket Tester, add the input the tool asks for, run it, and check the output before using it elsewhere.
Input and output
- Input: text.
- Output: text.
- Category: Network.
Privacy and processing
Processing happens locally in your browser. This tool does not upload the input to ilham.dev.
Questions
Why can I not connect to a ws:// address from this page?
Because the page is served over https, and a browser refuses to open an insecure WebSocket from a secure page — it would be a hole in the padlock. This is a mixed-content rule enforced by the browser, not a setting here. Use wss://, or run the test from a page served over plain http, or use a command-line client such as websocat for a local ws:// endpoint. The page allows ws:// to localhost, which browsers treat as trustworthy.
What does close code 1006 mean?
That the connection closed without a close frame — no proper handshake, no reason string. It is what you see when the server process died, a proxy dropped the connection, or the network went away, and it is deliberately not a code a server can send you. The log spells this out because 1006 on its own looks like a mystery number.
Can I send binary data?
Yes. Tick "Send as binary" and type the bytes as hex, and the page converts them to an ArrayBuffer before sending. Anything that is not valid hex is refused with a message rather than being sent as something else. Replies are labelled as text or binary in the log, and binary replies are shown as hex.
How do I connect with a subprotocol?
Type them in the subprotocol field, comma separated — for example chat, superchat. The server picks one and the log records which one it chose, which is the part people actually need to see when a handshake succeeds but the application protocol is wrong.
Related guide
For broader background, see Testing and Debugging WebSockets.