Zircos is a premium, fully responsive web app UI kit. It has flat design and built with Bootstrap 3.3.7, HTML5, CSS3 and Jquery. It comes with bunch of reusable UI widgets, components, ready made pages. The clean and modular code will allow you to easily build any web application.
Demo: https://themeforest.net/item/zircos-responsive-admin-template-material-design/17619506