Clay Mockups - Free set of beautiful device mockups for your designs
Mockuuups Studio - Fast and easy way to create product mockups on macOS, Windows and Linux.
Craftwork - A collection of User Interface resources made by Craftwork
Mockup Generator - Create attractive product screenshots with just a few clicks
AppLaunchpad - Create free beautiful screenshots for App store/Google play
Previewed - Beautiful mockups & graphics for your next app