Base UI Sketch Framework - Huge set of everything you need to design and prototype
Atomize React - An open source design system for ReactJS
SketchCasts - A weekly screencast, all about how to use Sketch
Framer - 🔥 Design real websites right on the canvas.
UiSketcher - Easily sketch user interface with your pen-enabled device!
BotUI - A JavaScript framework to build conversational UIs 🤖