Mockuuups Studio - Fast and easy way to create product mockups on macOS, Windows and Linux.
Sketch Extensions - An official collection of Sketch extensions & plugins
Mediamodifier - Create beautiful designs and product mockups in seconds.
Framer Inventory 3 for Sketch - Import states & export prototypes from Sketch to Framer
mockDrop - Is a webapp for creating free device mockups including your screenshots.
Remake - A way to make web apps with just HTML & CSS