k6
Modern load testing tool
The Lens
By Erik Loyd, SaaS CEO and former COO/CFO of an AWS Premier Partner.
Updated Sep 2026
k6 lets you write load tests in JavaScript and run them from the command line. No JMeter XML, no clunky GUI. Write a script, run k6 run script.js, and get latency and error numbers back in seconds.
Go, AGPL v3, owned by Grafana Labs since 2021. It speaks HTTP, WebSockets, gRPC and real browsers, and streams results to Prometheus, Datadog, InfluxDB, OpenTelemetry and most other observability stacks. Self-hosted has no cap on virtual users or test length beyond your hardware, and the official k6-operator spreads one test across a Kubernetes cluster when a single machine can't generate enough load.
Grafana Cloud k6 is the paid route when you want traffic from multiple regions without running the machines. Free gets 500 virtual user hours a month, and a 30-minute test at 100 virtual users burns 50 of them. Pro is $19/mo with the same 500 included, then $0.15 per hour. Enterprise starts at a $25,000/yr commit. Solo and small teams: the CLI in CI is all you need. Medium teams: Pro once you need geographic spread. Large teams: k6-operator or Enterprise.
The catch: AGPL. Running tests internally is fine. Building a testing product on a modified k6 means publishing your changes, so talk to a lawyer first.
Free vs Self-Hosted vs Paid
free self hosted paid cloudFree Tier
The k6 CLI is fully free: unlimited virtual users, unlimited test duration, all protocols. AGPL v3. Grafana Cloud's free tier adds 500 virtual user hours (VUh) per month of cloud execution, with 14 days of result retention.
Self-Hosted Costs
The CLI runs on a laptop or CI runner with nothing else to host. For load beyond one machine, the official grafana/k6-operator runs distributed tests on your own Kubernetes cluster, so the cost is the cluster time.
Paid (Grafana Cloud k6)
Pro: $19/mo platform fee including 500 VUh, then $0.150/VUh (dropping to $0.135 above 3,500 and $0.120 above 7,500). 30-day retention, 8x5 email support. Enterprise: Custom pricing on an annual commit, minimum $25,000/yr, scales to 1 million concurrent virtual users. The math: VUh = max virtual users x minutes / 60. A 30-minute test at 100 VUs = 50 VUh. Ten of those a month = 500 VUh, which fits inside Free or Pro's included hours.
When to Pay
It makes sense to pay when you need load from multiple geographic regions at once, or when running your own k6-operator cluster costs more in engineer time than Pro's metered hours.
CLI is free forever. Grafana Cloud k6 starts free at 500 virtual user hours a month, then $19/mo plus $0.15 per hour for multi-region runs.
What to do by team size
- Solo
- free; the CLI covers everything
- Small team
- free; run it from CI and export to Grafana
- Medium team
- free CLI, plus Cloud Pro at $19/mo when you need multi-region load
- Large team
- k6-operator on your own cluster, or Enterprise from $25,000/yr
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