Selenium - Selenium automates browsers. That's it! What you do with that power is entirely up to you. Primarily, it is for automating web applications for testing purposes, but is certainly not limited to just that.
WebLOAD - WebLOAD - The most flexible and cost effective software for enterprise load, stress and performance testing, integrated with DevOps processes. Click for details
Robot framework - Robot Framework is a generic test automation framework for acceptance testing and acceptance...
StresStimulus - Load testing tool for websites and mobile that works with hard-to-test applications.
Screenster - 10x faster UI testing without a line of code.
OctoPerf - OctoPerf is a SaaS load testing solution, based on JMeter.