Locust
Write load tests as plain Python. Scale by adding workers.
What it is
Locust defines user behaviour in ordinary Python classes, with no DSL or XML, and swarms the target using event-driven greenlets. A built-in web UI shows live statistics, and distributed mode scales across machines by starting more workers. If your team knows Python, there is essentially nothing to learn.
Best for
Product tour
See Locust in action
Explore the interface before you make an account. Screenshots come from official product materials and may change as the tool evolves.
Live request statistics
Watch request volume, failures, response times and current throughput while a load test runs.
Where it is strong
- 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.
Where it falls short
- 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.
Pricing
Free and open source
Open sourceFree tier: Everything, self-hosted
What drives the bill: Free and open source. You pay in engineering time and CI minutes.
Check current pricing on OSS community’s siteFigures are indicative and were last reviewed August 2026. Vendors change pricing often; confirm before you commit.
Works with
What people who use Locust say
No reviews of Locust yet. If you have used it in anger, yours would be the first.
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