The most popular front-end framework for developing responsive, mobile first projects on the web.
Website : http://getbootstrap.com/
The most advanced responsive front-end framework in the world.
Website : http://foundation.zurb.com/
Semantic empowers designers and developers by creating a language for sharing UI.
Semantic is a UI Component library implemented using a set of specifications designed around natural language. It provides many commonly needed elements, collections, and modules. It also provides a structure for third party components to use.
Website : http://semantic-ui.com/
Gumby 2.6 is built with the power of Sass. Sass is a powerful CSS preprocessor which allows us to develop Gumby itself with much more speed — and gives you new tools to quickly customize and build on top of the Gumby Framework.
Website : http://gumbyframework.com/
A set of small, responsive CSS modules that you can use in every web project.
Pure is a little set of CSS segments which you can use in any web project. This has small impact. It is developed with cellular in your mind and has now minimal design which enables you to write your very own style on top of it. With number of CSS components Pure is just one of the strong competitor for Responsive CSS Frameworks choices.
Website : http://purecss.io/