Ape Mockups - A huge hand-curated collection of free high-quality mockups
Mockuuups Studio - Fast and easy way to create product mockups on macOS, Windows and Linux.
AppLaunchpad - Create free beautiful screenshots for App store/Google play
Placeit - Generate realistic product shots in seconds
Clay Mockups - Free set of beautiful device mockups for your designs
Smartmockups - Create stunning product mockups, easily and online.