WebSocket Load Testing

Validate real-time connection performance

Open hundreds of concurrent WebSocket connections and exchange messages at scale. Measure connection establishment time, message latency, and throughput under load.

What you get

Concurrent WebSocket connection testing
Message send/receive latency tracking
Connection stability under load
Custom message payloads (JSON, binary)
Reconnection and error handling patterns
Compatible with Socket.io and raw WebSockets

websocket-test.js

import ws from 'k6/ws';
import { check } from 'k6';

export const options = { vus: 100, duration: '2m' };

export default function () {
  const res = ws.connect('wss://echo.example.com', {}, (socket) => {
    socket.on('open', () => {
      socket.send(JSON.stringify({ type: 'ping' }));
    });

    socket.on('message', (msg) => {
      check(msg, {
        'got response': (m) => m.length > 0,
      });
    });

    socket.setTimeout(() => socket.close(), 10000);
  });

  check(res, { 'connected': (r) => r && r.status === 101 });
}

Frequently Asked Questions

How many WebSocket connections can I test?

Each virtual user maintains one WebSocket connection. With 200 free VUs, you can test 200 concurrent connections. Scale to thousands on paid plans.

Does it work with Socket.io?

Yes. Socket.io uses WebSocket as the transport layer. You can test Socket.io servers by connecting to the WebSocket endpoint directly with appropriate handshake headers.