k6
Open-source load testing tool that scripts performance tests in JavaScript.
About
k6 is Grafana Labs' open-source load testing tool. Tests are plain JavaScript with a purpose-built API for virtual users, HTTP requests, checks, and thresholds, so you can fail a build when p95 latency or error rates cross your limits. It runs from the CLI, fits naturally into CI pipelines, and produces detailed metrics you can stream into Grafana, Datadog, or other backends.
The core is AGPL-3.0 licensed with 31,000+ GitHub stars and active development; Grafana Cloud k6 adds managed execution from 20+ geographic locations for teams that do not want to run load generators themselves. It is the default answer for load-testing LLM APIs and agent endpoints, where latency budgets and rate limits need verification before launch.
What it can do
- JavaScript test scripts with checks and thresholds
- Virtual users with configurable executors
- CI-friendly CLI with pass/fail exit codes
- Metrics export to Grafana, Datadog, and more
- Browser testing module for frontend performance
Setup
Install via package manager (brew install k6 on macOS) or Docker, write a test script, and run k6 run script.js.
Prerequisites
None for local runs; CI integration needs a runner. A Grafana Cloud account is optional for managed cloud runs.
Use cases
Works with
Trust score — 9/10
Scored 9/10 (verified tier, metrics-v1). Evidence: 31,941 GitHub stars; AGPL-3.0 license confirmed via GitHub API (not permissive); Grafana Labs backing; JS test scripts, thresholds, and CI integration verified against official docs. Manual review: Grafana Cloud k6 locations (20+) are provider-stated; AGPL copyleft matters for embedded use. License: AGPL-3.0.
★ 31,941 GitHub stars
Sources
Every fact above was checked against these sources. Where a claim comes from the provider and couldn't be independently verified, the text says so.