Project Wallace is a set of CSS analyzers that check your complexity, specificity, performance, Design Tokens and much more. And all of that in a single web app.

Stylify CSS is a library that uses CSS-like selectors to generate optimized Utility-First CSS dynamically based on what you write. It also allows you to define components, variables and global selectors.

Vue.js 2.3 Complete API online Cheat Sheet.