Performance Testing with k6: load and stress

What is k6?

k6 is a performance testing tool developed by Grafana. It lets you write load tests in JavaScript, run them from CLI or CI, and generate detailed metrics reports.

Installation and first test

brew install k6

import http from 'k6/http';
import { check, sleep } from 'k6';

export default function () {
  const res = http.get('http://localhost:3000/api/health');
  check(res, { 'status is 200': (r) => r.status === 200 });
  sleep(1);
}

Test types

• Smoke test: verifies system works with minimal load.
• Load test: simulates expected normal traffic.
• Stress test: pushes the system to find the breaking point.
• Spike test: sudden traffic increases.
• Soak test: sustained load for hours to detect memory leaks.

Scenario configuration

export const options = {
  stages: [
    { duration: '2m', target: 100 },
    { duration: '5m', target: 100 },
    { duration: '2m', target: 0 },
  ],
};

Key metrics

• http_req_duration: response time.
• http_req_failed: error percentage.
• vus: concurrent virtual users.
• iterations: completed iterations count.

Need performance testing? At Vynta we run load tests to ensure scalability.