Marvel - Turn sketches, mockups and designs into web, iPhone, iOS, Android and Apple Watch app prototypes.
Unsplash - Unsplash is a website with high-quality free HD images. It has a catalog of more than three hundred thousand striking images that are neatly organized with tags. Read more about Unsplash.
Zeplin - Collaboration app for UI designers & frontend developers
Pixabay - Over 270,000 free photos, vectors and art illustrations
Figma Product Planner - Easiest way to plan, visualize, & share your product planing
Openverse - Openverse is an Openly Licensed Images and Audio database and a growing community of photographers, illustrators, and musicians who share their work under a Creative Commons license.