Principle makes it easy to create animated and interactive user interface designs. Whether you're designing the flow of a multi-screen app, or new interactions and animations […]
… a desktop app that lets you build responsive websites faster with live multi-page editing, CSS styling and smart components for Bootstrap, Foundation, AngularJS and WordPress.
… a specialized remote screen viewing application intended as a tool to help designers create graphics for mobile applications, it has also proven to be useful for creating quick and dirty simulations, demos, and experience prototypes.
compile Compass/Sass easily without resorting to command line interface — Compass.app helps designers compile stylesheets easily without resorting to command line interface. It is written in Java and works in Windows/Linux/Mac OS X.
Icon Composer 2x is a replacement for Apple's Icon Composer that supports Retina Resolution Icons. On GitHub: https://github.com/lemonmojo/IconComposer2x
… a simple app which allows you to change your system icons quickly and easily. Simply drag an icon onto the one you want to change, and click the Apply Changes button. That's it. To restore an icon by the original, just drag it out.