Now UI Kit - A beautiful Bootstrap 4 UI kit. Yours free.
Dashboard UI Kit - A modern & responsive dashboard UI kit for designers.
Bots UI Kit - Fully customizable Sketch UI Kit for Messenger Platform
Loop Design UI kit V2 - A free UI kit for busy designers and startup owners
Landing UI Kit - Handcrafted UI components for landing pages
Contrast Design Bootstrap React - Elegant reusable components library for mobile-first webapps