mirador : Mirador is a tool for visual exploration of complex datasets. It enables users to discover correlation patterns and derive new hypotheses from the dat...
Sizzy : A tool for developing responsive websites crazy-fast.
Open sourced : https://github.com/kitze/sizzy
PurgeCSS : PurgeCSS is a tool to remove unused CSS. It can be part of your development workflow.
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...
WhatWeb : WhatWeb identifies websites. Its goal is to answer the question, “What is that Website?”. WhatWeb recognises web technologies including content manage...
csscss will parse any CSS files you give it and let you know which rulesets have duplicated declarations.