Watir, pronounced water (acronym standing for "Web Application Testing in Ruby"), is an open-source (BSD) family of Ruby libraries for automating web browsers. It allows you to write tests that are easy to read and maintain. It is simple and flexible.
Watir drives browsers the same way people do. It clicks links, fills in forms, presses buttons. Watir also checks results, such as whether expected text appears on the page. More Info »
Watir is a family of Ruby libraries but it supports your app no matter what technology it is developed in. They support Internet Explorer on Windows, Firefox and Chrome on Windows, Mac and Linux and Safari on Mac.