Design Principles - An open source repository of design principles and methods
Really Good UX - A library of screenshots for UX inspiration
UX Research Field Guide - Your map to the world of UX research 🌏🕵️♀️
Usability.gov - Resource for user experience (UX) best practices & guides
UX Design Weekly - The best user experience links each week to your inbox
UX Check - Easy heuristic evaluations on your website (chrome ext.)