Smartmockups - Create stunning product mockups, easily and online.
Device Shots - Generate high-resolution device mockups using a screenshot.
AppLaunchpad - Create free beautiful screenshots for App store/Google play
Facebook Design - Devices - Images and Sketch files of popular devices.
Placeit - Generate realistic product shots in seconds
Mockuuups Studio - Fast and easy way to create product mockups on macOS, Windows and Linux.