Free & OpenSource REST API Testing Tool for all levels in a Test Pyramid

Checks web UI for browser compatibility (Compliance with Can I Use?)

k6 Open Source is designed for load testing. Extensible to support other types of testing.

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.

Simple animated GIF screen recorder with an easy to use interface.

Robot Framework is a generic open source automation framework. It can be used for test automation and robotic process automation (RPA).