Invision - Prototyping and collaboration for design teams
Device Shots - Generate high-resolution device mockups using a screenshot.
Mockuuups Studio - Fast and easy way to create product mockups on macOS, Windows and Linux.
Facebook Design - Devices - Images and Sketch files of popular devices.
Craftwork - A collection of User Interface resources made by Craftwork
Dashboard UI Kit - A modern & responsive dashboard UI kit for designers.