Interfacer - Collection of more than 200+ free design resources
Really Good UX - A library of screenshots for UX inspiration
Freebiesbug - Collection of the best free web design resources.
Usability.gov - Resource for user experience (UX) best practices & guides
UI HUT - 12,000+ exclusive design resources for Figma, Sketch & XD
UX Check - Easy heuristic evaluations on your website (chrome ext.)