Grafana k6 vs Locust

From $19 per month (indicative, Grafana Cloud k6 entry)

Free and open source

Self-hosted is free and unlimited. Cloud plans are billed by virtual-user-hours, which is where budgets go.

Free and open source. You pay in engineering time and CI minutes.

The k6 CLI is fully open source with no virtual-user limits when self-run.

Everything, self-hosted

Category standard

Grafana Labs · since 2016

Widely used

OSS community · since 2011

• Excellent resource efficiency — thousands of virtual users from one modest machine.
• Thresholds make performance a build gate rather than a report nobody reads.
• Native Grafana and Prometheus integration ties load results to server-side metrics.

• Test scenarios are plain Python, so any logic is expressible without workarounds.
• Distributed mode is conceptually simple and works well on Kubernetes.
• Live web UI is useful during an exploratory ramp-up.

• The JavaScript runtime is not Node — no npm modules unless bundled, which surprises people.
• Browser-level load testing exists but is much heavier and less mature than protocol-level testing.
• Distributed execution requires either the cloud product or your own orchestration.

• Python's per-user overhead is higher than k6 or Gatling; big loads need more machines.
• Reporting is basic — plan on exporting to Grafana.
• HTTP-centric; other protocols require writing your own client.

Engineering teams that want performance regression tests running in CI.

Python teams who want load scenarios expressed in their own language.