Bootstrap Magic - Create your Bootstrap 4.0 themes easily with magic
React Boilerplate - Offline-first, highly scalable foundation for your next app
Bootstrap Studio - Powerful desktop app for creating responsive websites using the Bootstrap framework
GatsbyJS - Blazing-fast static site generator for React
Designmodo - Timesaving tools for designers, developers and marketers. Designmodo offers website and email builders.
Teutonic CSS - Here’s 12KB of CSS to jump start your HTML