Base UI Sketch Framework - Huge set of everything you need to design and prototype
Device Shots - Generate high-resolution device mockups using a screenshot.
INSTAD.IO - Automagically converts vector images into sketchy style
shotsnapp - Create beautiful device mockup presentation
Sketch Extensions - An official collection of Sketch extensions & plugins
Graphcool - The GraphQL backend for mobile & web developers to build better apps faster ⚡️