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.

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

Flawless Test Automation connected with DevOps

For those more detailed screen recordings like demos as well as bugs. Has a built in editor.

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

Best "simple" screen capturing app (Mac and Windows) because it creates animated gifs that attach to bugs easily. Simple because it works a lot like snippy to capture screen areas