React Rainbow Components - Build your web application in a snap.
Tetrisly - Starter kit for design systems and wireframes builder (Sketch/Figma)
Recharts - Redefined chart library built with React and D3
Material Design Icons - 750 Free open-source glyphs by Google
NativeBase - Experience the awesomeness of React Native without the pain
Reakit - A toolkit to build accessible web apps with React