Bootflat is a open source Flat UI KIT based on Bootstrap CSS framework. It provides a faster, easier and less repetitive way for web developers or designers to create elegant web apps. Bootflat is built on the foundations of Bootstrap, visioned in a stunning flat design. Bootstrap itself is a trusted, reliable and proven tool for developers.
Bootflat is built on Bootstrap 3.1.1: the sleek, intuitive, and powerful mobile-first front-end framework for faster and easier web development.
Bootflat is fully responsive, built for mobile-first in mind. It provides off screen navigation, and almost all the widgets are compatible with all screen sizes.
For the designers, they also offer a free PSD file for you, it including a set of beautiful and pure components, which you can use to create startup projects, websites or iOS/Android Apps.