Applications

Codekit (Mac)
- http://incident57.com/codekit/
- LESS, Sass/SCSS, HAML, Jade, Image Optimization, etc. Paid
Prepros (Mac/PC/Chrome Extension)
- http://alphapixels.com/prepros/
- Compiles LESS, Sass, SCSS, Stylus, Jade, Slim, Coffeescript, LiveScript, Haml and Markdown. Free
Koala (Mac/PC/Linux/Ubuntu)
- http://koala-app.com/
- Supports Less, Sass, CoffeeScript and Compass. Free
Hammer (Mac)
- http://hammerformac.com/
- Built-in support for Sass (with Bourbon), CoffeeScript, HAML & Markdown. Paid
Scout.app (PC/Mac)
- http://mhs.github.com/scout-app/
- Compass and Sass compiler. Free
Compass.app (PC/Mac/Linux)
- http://compass.handlino.com/
- Compass and Sass compiler. Paid
WinLESS (PC)
- http://winless.org/
- Windows GUI for LESS.js. Free
SimpLESS (Mac/PC) —
- http://wearekiss.com/simpless
- LESS compiler. Free
LiveReload (Mac/PC)
- http://livereload.com
- Monitors changes in the files system. As soon as you save a file, it is preprocessed as needed and the browser is refreshed without reloading the page. Paid

cdharrison/preprocessor-apps.md