Development & Testing

k6 Load Testing

Run load and performance tests with k6, scripting scenarios in JavaScript to simulate thousands of virtual users.

Claude Code Codex Cursor Gemini CLI

Overview

k6 is a modern load testing tool that uses JavaScript for test scripting, making it accessible to developers who are already comfortable with the language. Unlike JMeter or Gatling, k6 scripts are just ES6 modules that define virtual user behavior, HTTP requests, and performance thresholds. AI agents can generate comprehensive load test scenarios from API documentation or endpoint definitions.

Your AI agent can write k6 scripts that simulate realistic user journeys: authentication flows, CRUD operations, file uploads, and WebSocket connections. It can configure ramping scenarios (gradual increase, spike testing, soak testing), set performance thresholds (p95 response time under 500ms), and analyze the output to identify bottlenecks.

k6 integrates with Grafana for real-time dashboards, supports custom metrics, and can export results to various backends for historical analysis. Your AI agent can configure these integrations, write custom check functions to validate response data, and help you interpret test results to determine whether your application can handle the expected load.

Who Is This For?

Performance engineers load-testing APIs before major releases
Backend developers identifying bottlenecks under concurrent user load
DevOps teams integrating load tests into CI/CD pipelines with threshold gates
Teams running soak tests to detect memory leaks in long-running services

Installation

Setup for Claude Code

brew install k6  # macOS
Claude Code writes k6 scripts and runs: k6 run script.js

Configuration

// load-test.js
import http from "k6/http";
import { check, sleep } from "k6";

export const options = {
  stages: [
    { duration: "30s", target: 20 },
    { duration: "1m", target: 100 },
    { duration: "30s", target: 0 },
  ],
  thresholds: {
    http_req_duration: ["p(95)<500"],
    http_req_failed: ["rate<0.01"],
  },
};

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