CodeKit - CodeKit allows you to optimize the performance of your website by automatically and efficiently compiling a variety of popular languages.
Bootstrap - Simple and flexible HTML, CSS, and JS for popular UI components and interactions
Prepros - Compile Less, Sass, Scss, Stylus, Jade, Coffeescript, Haml and Markdown with live browser refresh.
Foundation - The most advanced responsive front-end framework in the world
Scout-App - Process Sass files into CSS without any knowledge of the command line.
Semantic UI - A UI Component library implemented using a set of specifications designed around natural language