Need a GUI application for Less, Sass, Compass and CoffeeScript compilation (Prepros is not Open Source).
Name: Koala
Homepage: http://koala-app.com/
Is it Open Source: yes
Link to source tarball/zip file: https://github.com/oklai/koala/releases/download/v2.3.0/koala_2.3.0_x86_64.tar.gz