CSS Lint : CSS Lint points out problems with your CSS code. It does basic syntax checking as well as applying a set of rules to the code that look for problemati...
ESLint : The pluggable linting utility for JavaScript and JSX
csscss : csscss will parse any CSS files you give it and let you know which rulesets have duplicated declarations.
Galen Framework : Automated testing of look and feel for your responsive websites.
Layout testing seemed always a complex task. Galen Framework offers a simple solution...
PurgeCSS : PurgeCSS is a tool to remove unused CSS. It can be part of your development workflow.
A mighty, modern CSS linter that helps you enforce consistent conventions and avoid errors in your stylesheets.