I’ve been playing with a cool little application called Dash for a while now. It’s a hotkey-based popup with configurable docsets for most major programming languages, including HTML, CSS (plus Less, Bourbon, Compass, Sass, etc.), JavaScript, Cocoa (Mac and iOS), Python, PHP, Ruby, Unix man pages and much more. It also has an iCloud/Dropbox-syncable snippet manager for storing and quickly accessing reusable code, complete with placeholders and cursor location control.
This is a companion discussion topic for the original entry at https://brettterpstra.com/2013/04/26/mac-app-review-dash-for-developers