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.

Watir - Watir stands for Web Application Testing In Ruby. It facilitates the writing of automated tests by mimicking the behavior of a user interacting with a website. CommunityWatir stands for Web Application Testing In Ruby.

Robot framework - Robot Framework is a generic test automation framework for acceptance testing and acceptance...

Retest - Retest allows you to check your web apps user experience and deliver absolute masterpieces on multiple devices so that every time your customer visits your webpage, they feel what you want them to feel with your design irrespective of their device

TestComplete - TestComplete Desktop, Web, and Mobile helps you create repeatable and accurate automated tests across multiple devices, platforms, and environments easily and quickly.