# Locust

> Locust is an open source, self-hosted load testing tool from Locust authors, scripted in Python.

- Canonical: https://perf.jmeter.ai/tools/locust/
- Review: https://perf.jmeter.ai/reviews/locust/
- Official: https://locust.io/
- Source: https://github.com/locustio/locust
- Vendor: Locust authors
- Category: Load Testing
- License: Open Source — Free; MIT License.
- Deployment: Self-hosted
- Status: Active
- Scripting: Python
- Protocols: HTTP, HTTPS, WebSocket
- OS support: Windows, macOS, Linux
- First released: 2011
- Latest release: 2.46.2 (2026-07-24)
- Last verified: 2026-08-11

## What it is
Locust lets engineers describe user behavior in ordinary Python code. Tests can run distributed across processes or machines and expose an HTTP web interface.

## Choose it when
- Load Testing scenarios across typical web and service stacks
- Teams that prefer open-source licensing and self-hosting options
- Groups comfortable scripting in Python

## Look elsewhere when
- Teams unwilling to operate generators, results storage, and scaling

## Architecture
Locust is commonly operated as self-hosted software with scenario authoring in Python. Concurrency and distribution depend on how you size workers or injectors.

## Pricing
The open-source core of Locust is free. Separately, Locust Cloud offers paid, usage-based SaaS plans for hosted infrastructure and reporting.

## Compare
- [Locust vs k6](https://perf.jmeter.ai/vs/locust-vs-grafana-k6/) — Choose Locust when Python is the team language and you want flexible user tasks.
- [Apache JMeter vs Locust](https://perf.jmeter.ai/vs/apache-jmeter-vs-locust/) — The practical split is the authoring language: Java, Groovy for Apache JMeter, Python for Locust.
- [Locust vs LoadRunner Professional](https://perf.jmeter.ai/vs/locust-vs-loadrunner-professional/) — The practical split is the cost model: Locust is open source, LoadRunner Professional is commercial.
- [Locust vs NeoLoad](https://perf.jmeter.ai/vs/locust-vs-neoload/) — The practical split is the cost model: Locust is open source, NeoLoad is commercial.
- [Locust vs BlazeMeter](https://perf.jmeter.ai/vs/locust-vs-blazemeter/) — The practical split is the cost model: Locust is open source, BlazeMeter is commercial.
- [Locust vs Tsung](https://perf.jmeter.ai/vs/locust-vs-tsung/) — The practical split is the authoring language: Python for Locust, Erlang, XML for Tsung.
- [Locust vs The Grinder](https://perf.jmeter.ai/vs/locust-vs-the-grinder/) — The practical split is the authoring language: Python for Locust, Jython, Java for The Grinder.
- [Locust vs Azure Load Testing](https://perf.jmeter.ai/vs/locust-vs-azure-load-testing/) — The practical split is the cost model: Locust is open source, Azure Load Testing is commercial.
- [Locust vs AWS Distributed Load Testing](https://perf.jmeter.ai/vs/locust-vs-aws-distributed-load-testing/) — The practical split is who runs the load generators: Locust on your own infrastructure, AWS Distributed Load Testing on the vendor's.
- [Locust alternatives](https://perf.jmeter.ai/alternatives/locust/)

## FAQ
### Who is Locust for?
Locust is best for engineers designing load, stress, and performance tests for web and service systems. It is open source, so teams can self-host and extend it. Vendor: Locust authors. Deployment model: self-hosted. Free; MIT License. Confirm details against the official site and a short proof-of-concept in your environment.

### How does Locust differ from Apache JMeter?
Compared with Apache JMeter, scripting centers on Python rather than Java, Groovy. Locust lists protocols HTTP, HTTPS, WebSocket; Apache JMeter lists HTTP, HTTPS, JDBC, JMS, FTP, TCP. Status is active versus active. Use the Test Rig to compare full specs side by side before a proof-of-concept.

### What scripting language and concurrency model does Locust use?
Locust uses Python for scripting or scenario definition. Runtime model: code-first scenarios where virtual users execute scripted behavior under load. OS support: Windows, macOS, Linux. Protocols: HTTP, HTTPS, WebSocket. Match these to how your team already authors tests and which systems you must drive under load.

### What is the cloud or enterprise path for Locust?
Locust is primarily self-hosted; teams typically run generators on their own machines, CI runners, or private cloud. Plan for generator capacity, network access to targets, and result storage yourself. As open source, commercial support or hosted siblings may exist separately. Check the official site. Pricing note: Free; MIT License.

### What are known limitations of Locust?
Locust limitations to weigh: self-hosted tools require you to provision, scale, and observe load generators yourself. Status: active. Always validate against your target protocols and scale with a proof-of-concept. Confirm details against the official site and a short proof-of-concept in your environment.

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Curated by NaveenKumar Namachivayam (QAInsights) · methodology: https://perf.jmeter.ai/about/#methodology · corrections: https://github.com/QAInsights/Performance-Testing-Tools/issues/new?title=Tool%20submission%3A%20&body=Tool%20name%3A%20%0AOfficial%20URL%3A%20%0AWhat%20should%20be%20added%20or%20corrected%3F%20%0A