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

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

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

YATTIE exists to help make tester's lives easier. Ideally, it should remove friction from the exploratory testing process - everywhere from gathering evidence to submitting reports.

Bruno is a Fast and Git-Friendly Opensource API client, aimed at revolutionizing the status quo represented by Postman, Insomnia and similar tools out there.

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