It is the one which minifies css and js files.

• YUI Compressor

If you are a Mac user and have homebrew installed, just do

brew install yuicompressor

(If not, fetch .jar file from the link above.)

Then, do

yuicompressor foo.js -o foo.min.js

Basially, that’s all.

If you want specify encoding, do

yuicompressor foo.js -o foo.min.js --charset shift_jis

Very easy and effective.