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.

A screenshot/screenvideo tool! Also allows you to do basic alterations to the screenshots (arrows, blur, ...)

The world’s first API testing platform that auto-generates unit test cases with dependency mocks from API calls. Using advanced AI, it simplifies test creation, debugging, and evolution, ensuring comprehensive coverage and boosting software quality.

Orderly Ape is an open source (MIT) tool to run distributed and scalable k6 load tests on your own infrastructure using k6, kubernetes, grafana and influxdb.

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).

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