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.
placeholder.pics - Lightest way to include placeholder images in your design
Pixabay - Over 270,000 free photos, vectors and art illustrations
PlaceKitten - Dead-easy placeholder images. Of kittens.
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.
Fill Murray - Custom-sized placeholder images of Bill Murray