Gatling is a powerful open-source load testing solution that integrates with your development pipeline. It includes a web recorder and colorful reports.

WebLOAD – Performance and Load Testing for the Most Challenging Web Applications

Built for developers and testers alike, SoapUI is the only open source tool that covers the entire testing spectrum (functional, security, load, mocking).

The Complete Continuous Testing Platform Any test. Any device. App quality without limits.

Simplifies performance and load testing so that application delivery teams can take a standardized approach to ensure continuous performance, reliability, and scalability from development to production.

The Apache JMeter™ application is open source software, a 100% pure Java application designed to load test functional behavior and measure performance. It was originally designed for testing Web Applications but has since expanded to other test functions.