Mockuuups Studio - Fast and easy way to create product mockups on macOS, Windows and Linux.
Facebook Design - Devices - Images and Sketch files of popular devices.
Smartmockups - Create stunning product mockups, easily and online.
Device Shots - Generate high-resolution device mockups using a screenshot.
MockMagic - A free, easy-to-use device mockup generator
Clay Mockups - Free set of beautiful device mockups for your designs