Locust

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Score7.1

Rank#3 of 34

PriceFree

Free planYes

Runs onAPI, Linux, macOS, Self-hosted, Web, Windows

Summary

Locust is a free, open-source tool for performance and load testing HTTP services and other protocols. Test scenarios are written in Python, so you can use regular Python libraries in them. Run a test from the command line or web interface, where throughput, response times, errors, and progress appear in real time. The interface also lets you adjust load while a test is running, and results can be exported for later analysis. Locust can distribute tests across multiple machines and says it can support hundreds of thousands of concurrent users. You can extend it to cover other systems and protocols by adding a client; its documentation also lists community extensions for protocols and reporting. Optional OpenTelemetry support exports traces, metrics, and logs to compatible backends such as OTLP, Prometheus, Jaeger, and Tempo. Automatic instrumentation currently covers the requests library. Installation is documented with pip install locust, with uvx as an alternative. Locust uses the MIT license and is available through command-line and web interfaces.

Who it is for

Locust suits teams that want to write load-test scenarios in Python and monitor results while tests run. Its distributed execution and protocol extensions may suit testing across multiple machines or systems.

What is good

Free and MIT-licensed
Write scenarios in regular Python
Adjust load during a running test
Distribute tests across multiple machines
Export OpenTelemetry data to compatible backends

What to know first

Automatic instrumentation currently covers requests only
Other protocols require adding a client

Verdict

Locust combines Python-authored scenarios with live results and distributed execution. Check whether its requests-only automatic instrumentation covers your needs before relying on telemetry without additional setup.

Locust plans and pricing

All plans

Locust Free Open source · MIT license docs.locust.io · 30 Sept 2026

Compared on performance testing software

Free plan: Yeslocust.io
Load testing: Yeslocust.io
Stress testing: Yeslocust.io
Browser-based testing: Yeslocust.io
Distributed load: Yeslocust.io
API testing: Yeslocust.io
Deployment model: hybridlocust.io

Facts

Purpose: Locust is an open-source performance and load testing tool for HTTP and other protocols.docs.locust.io · 30 Sept 2026
Test authoring: Users define test scenarios in regular Python code and can use regular Python libraries in their tests.docs.locust.io · 30 Sept 2026
Execution and reporting: Tests run from the command line or web interface, which displays throughput, response times, and errors in real time; results can also be exported for later analysis.docs.locust.io · 30 Sept 2026
Scale: Locust supports distributed tests across multiple machines and says it can support hundreds of thousands of concurrent users.docs.locust.io · 30 Sept 2026
Load adjustment: The web interface shows test progress in real time and allows load to be changed while a test is running.docs.locust.io · 30 Sept 2026
Protocol extensibility: Locust can test other systems and protocols by adding a client, and its documentation lists community extensions for protocols and reporting.docs.locust.io · 30 Sept 2026
Integrations: Optional OpenTelemetry support exports traces, metrics, and logs to compatible backends, including OTLP, Prometheus, Jaeger, and Tempo.docs.locust.io · 30 Sept 2026
OpenTelemetry limit: Automatic instrumentation currently covers the requests library, so HttpUser requests generate spans and metrics without additional configuration.docs.locust.io · 30 Sept 2026
Hosted option: Locust documentation describes hosted load testing through Azure Load Testing, with built-in reporting, Azure Application Insights integration, and CI/CD support for Azure DevOps and GitHub Actions.docs.locust.io · 30 Sept 2026
Installation: The documented installation method is pip install locust, with uvx also offered as an alternative.docs.locust.io · 30 Sept 2026
Support: The project README directs support questions to Stack Overflow and discussion to Discord, while locust.io says Locust.cloud provides dedicated commercial support.github.com · 30 Sept 2026
License: Locust is licensed under the MIT license.docs.locust.io · 30 Sept 2026