Design Principles - An open source repository of design principles and methods
InVision Studio - The world’s most powerful screen design tool
Facebook Design Resources - A collection of free resources made by designers at Facebook
Figma - Team-based interface design, Figma lets you collaborate on designs in real time.
Facebook - Connect with friends, family and other people you know. Share photos and videos, send messages and get updates.
Circular Design Guide - Toolkit that brings design thinking full circle