Sass is described as 'stylesheet language initially designed by Hampton Catlin and developed by Nathan Weizenbaum. After its initial versions, Nathan Weizenbaum and Chris Eppstein have continued to extend Sass with SassScript, a simple scripting language used in Sass files' and is an app in the development category. There are four alternatives to Sass for a variety of platforms, including Online / Web-based, Self-Hosted solutions, Windows, Linux and Mac. The best alternative is Stylus CSS, which is both free and Open Source. Other great apps like Sass are CSS, LESS and PostCSS.