Built by Twitter, Bootstrap was made to look and behave great on desktop, tablet, and smartphone browsers alike. From interactive widgets to responsive grid layouts, Bootstrap provides you with a complete toolset for building web sites and applications.
Created by ZURB, Foundation provides you with a complete set of widgets and styles to help you make the leap from low-fidelity concept to a polished product.
Based on the official Google Android design toolkit, these stencils provide you with everything you need to create compelling prototypes for Android mobile devices. Updated for Android 4.2 ( Jelly Bean ).
High fidelity stencils for Apple iOS-based devices, including the iPhone, iPad, and iPod Touch. All elements support retina and normal screens.
Stencils for designing for Apple iOS-based devices, including iPhone, iPad and iPod touch. The stencils include links to the Apple developer guides.
Pixel-accurate stencils for Microsoft Windows Phone devices, based on the official design guidelines.