Susy is described as ': un-obtrusive grid system for designers, built on Compass and Sass' and is an website in the Development category. There are more than 50 alternatives to Susy, not only websites but also apps for a variety of platforms, including Self-Hosted solutions, Mac, Windows and Linux. The best alternative is Bootstrap, which is both free and Open Source. Other great sites and apps similar to Susy are Bulma (Free, Open Source), Materialize (Free, Open Source), UIkit (Free, Open Source) and Semantic UI (Free, Open Source).
A unified, HTML5-based user interface system for all popular mobile device platforms, built on the rock-solid jQuery and jQuery UI foundation. Its lightweight code is built with progressive enhancement, and has a flexible, easily themeable design.