Flowkit - Sketch library for user flows/content maps/annotations
Sketch Mirror - Preview your iOS designs directly on your devices
Eva Design System - A free customizable design system
Sketch 101 by Designlab - Learn Sketch in this free course w/ downloadable templates
Figma Mirror - Figma Mirror is an application that covers top trending designing or sketching ideas making your teamwork in a single environment and design better products from start to finish.
Sketch Repo - Collection of resources for anyone who uses Sketch