Design Principles - An open source repository of design principles and methods
Responsive Viewer - View multiple screen dimensions in one view
UX Research Field Guide - Your map to the world of UX research 🌏🕵️♀️
Responsinator - Designed to test responsive websites on different devices.
Business-Driven Digital Product Design - A guide on how to create influential user experience
Responsive Website Test - Test any website on desktop, mobile, and tablet