Capturing WebSocket messages using headless browser automation

[WhisperingWind]

I’m trying to extract WebSocket data from a cryptocurrency trading platform. The issue I’m facing is that the WebSocket connection URL changes dynamically and becomes invalid after the initial connection. When I try to connect a second time, no data gets transmitted.

I’ve noticed that the WebSocket endpoint generates a new URL each time, which makes it impossible to directly connect to it multiple times. The connection works perfectly on the first attempt but fails to receive any messages on subsequent connections.

I’m wondering if using a headless Chrome browser could help me intercept and monitor the WebSocket traffic as it happens in real-time. Has anyone successfully captured WebSocket data using browser automation tools like this?

const browser = await chromium.launch();
const page = await browser.newPage();

// Listen for WebSocket frames
page.on('websocket', ws => {
  ws.on('framereceived', event => {
    console.log('Received:', event.payload);
  });
});

await page.goto('https://trading-site.com');

Any suggestions on how to properly monitor WebSocket communications through headless browsing?

[lucasg]

WebSocket monitoring through headless browsers definitely works here. I’ve done similar stuff for financial data and found Playwright’s network interception beats just listening to websocket events. Use page.route() to intercept the initial WebSocket handshake - you’ll capture auth headers and tokens during connection setup. Here’s the thing: don’t reconnect manually. Just monitor the page’s network activity to see when the original WebSocket drops and a new one gets established by the platform’s reconnection logic. Your headless browser should be a passive observer riding along with the natural connection lifecycle. One gotcha - some exchanges send binary frames that need special handling. Check the frame type before parsing as JSON. Also try --disable-web-security flag if you’re hitting CORS issues during development, but remove it for production.

[Oscar64]

Had the same issue with a different trading platform last year. Those dynamic URLs are actually a security feature - exchanges use them to block unauthorized connections. Here’s what worked for me: keep your browser session alive through the entire data collection instead of reconnecting. Don’t close and reopen connections. Just leave the headless browser running and let it handle the WebSocket lifecycle on its own. The platform’s JavaScript will manage reconnections and URL refreshes automatically. I tried manually intercepting and reusing URLs but it usually fails - they’ve got session tokens or timestamps that expire fast. Watch out though - some platforms detect headless browsers and will block WebSocket data. You’ll probably need to configure user agents and other fingerprinting details to fly under the radar. Also build in proper error handling for disconnects since most platforms have their own reconnection logic your code needs to work with.

[emmat83]

Browser automation works great here, but watch out for detection. Use page.setExtraHTTPHeaders() to mimic real browser requests and handle framesent events - some platforms check for two-way communication. Pro tip: inject custom JS that hooks into the native WebSocket constructor. You’ll get way more control than relying on Playwright’s listeners alone.