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Locust

locust.io

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Spec score 7.9 #15 of 33 in Software Testing Tools

What it is

Locust is an open-source performance and load testing tool for HTTP and other protocols. Test scenarios are written in Python, with regular Python libraries available for use within them. Tests can run from the command line or web interface, which displays throughput, response times, and errors in real time; results can be exported for later analysis. The interface shows progress and lets users change load during a run. Locust can distribute tests across multiple machines and says it can support hundreds of thousands of concurrent users. Other systems and protocols can be tested by adding a client, and documentation 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 or uvx. Locust is free and MIT-licensed. Its documentation also describes hosted load testing through Azure Load Testing, with reporting, Application Insights integration, and CI/CD support for Azure DevOps and GitHub Actions.

Spec sheet

Purpose
Locust is an open-source performance and load testing tool for HTTP and other protocols.Read 30 Sep 2026 · docs.locust.io
Integrations
Optional OpenTelemetry support exports traces, metrics, and logs to compatible backends, including OTLP, Prometheus, Jaeger, and Tempo.Read 30 Sep 2026 · docs.locust.io
Support
The project README directs support questions to Stack Overflow and discussion to Discord, while locust.io says Locust.cloud provides dedicated commercial support.Read 30 Sep 2026 · github.com
License
Locust is licensed under the MIT license.Read 30 Sep 2026 · docs.locust.io
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.Read 30 Sep 2026 · docs.locust.io
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.Read 30 Sep 2026 · docs.locust.io
Installation
The documented installation method is pip install locust, with uvx also offered as an alternative.Read 30 Sep 2026 · docs.locust.io
Load adjustment
The web interface shows test progress in real time and allows load to be changed while a test is running.Read 30 Sep 2026 · docs.locust.io
OpenTelemetry limit
Automatic instrumentation currently covers the requests library, so HttpUser requests generate spans and metrics without additional configuration.Read 30 Sep 2026 · docs.locust.io
Protocol extensibility
Locust can test other systems and protocols by adding a client, and its documentation lists community extensions for protocols and reporting.Read 30 Sep 2026 · docs.locust.io
Scale
Locust supports distributed tests across multiple machines and says it can support hundreds of thousands of concurrent users.Read 30 Sep 2026 · docs.locust.io
Test authoring
Users define test scenarios in regular Python code and can use regular Python libraries in their tests.Read 30 Sep 2026 · docs.locust.io

Plans and prices

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

Every Locust plan and price →

Strong points and limits

Strong points

  • Free and MIT-licensed
  • Test scenarios use Python and its libraries
  • Web interface reports throughput, response times, and errors
  • Load can be adjusted during a run
  • Distributed testing is supported

Limits

  • Automatic OpenTelemetry instrumentation currently covers only requests
  • Other protocols require adding a client
  • Support questions are directed to Stack Overflow

Who it suits

Locust suits developers who can author test scenarios in Python and need to observe HTTP or other protocol performance. Teams can run tests locally or distribute them across multiple machines.

Verdict

Locust offers Python-authored tests, live reporting, and distributed execution without a listed plan charge. Its automatic OpenTelemetry instrumentation is limited to requests-library activity.

Where Specifiction places it

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