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.
Screenster - 10x faster UI testing without a line of code.
DalekJS - DalekJS is an open source UI testing tool.
Robot framework - Robot Framework is a generic test automation framework for acceptance testing and acceptance...
Webinject - WebInject is a free tool for automated testing of web applications and web services.
TestComplete - TestComplete Desktop, Web, and Mobile helps you create repeatable and accurate automated tests across multiple devices, platforms, and environments easily and quickly.