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.

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

Automation Test Reporting. OSS, Language & Framework agnostic

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

SeleniumBase Case Plans is Test Case Management Software that uses Markdown tables for displaying test plans directly in GitHub (and other source code management systems that support Markdown format).