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.
Axure - The most powerful way to plan, prototype and hand off to developers, all without code. Download a free trial and see why professionals choose Axure RP 9.
Screenster - 10x faster UI testing without a line of code.
Balsamiq - Balsamiq. Rapid, effective and fun wireframing software.
Robot framework - Robot Framework is a generic test automation framework for acceptance testing and acceptance...
Moqups - The most stunning HTML5 app for creating resolution-independent SVG mockups, wireframes & interactive prototypes for your next project