Chrome
F12 > Audits >
Firefox
https://addons.mozilla.org/en-US/firefox/addon/dust-me-selectors/
Online
https://unused-css.com/
Desktop CSS Analyzer
http://sourceforge.net/projects/cssscanner/
CSS Formatter & minifier
http://www.cleancss.com/
node.js w/ Grunt
http://deanhume.com/home/blogpost/automatically-removing-unused-css-using-grunt/6101
ref - https://github.com/addyosmani/grunt-uncss
optimized - https://github.com/giakki/uncss