placeholder.pics - Lightest way to include placeholder images in your design
Mockuuups Studio - Fast and easy way to create product mockups on macOS, Windows and Linux.
PlaceKitten - Dead-easy placeholder images. Of kittens.
Mediamodifier - Create beautiful designs and product mockups in seconds.
Fill Murray - Custom-sized placeholder images of Bill Murray
Design Camera - Drag and drop 3D mockups