MockMagic - A free, easy-to-use device mockup generator
Artboard Studio - Online graphic design app mainly focused on product mockups.
Mockup Generator - Create attractive product screenshots with just a few clicks
Canva - Canva is a graphic-design platform with a drag-and-drop interface to create print or visual content while providing templates, images, and fonts. Canva makes graphic design more straightforward and accessible regardless of skill level.
Dimmy.Club - Device mockup generator for your website and app screenshots
Snappa - The perfect graphic design tool for digital marketers.