Now UI Kit - A beautiful Bootstrap 4 UI kit. Yours free.
Cuba - Cuba is a Ruby microframework for web development.
Bots UI Kit - Fully customizable Sketch UI Kit for Messenger Platform
Ramaze - Ramaze is a very simple and straight-forward web-framework.
Landing UI Kit - Handcrafted UI components for landing pages
NYNY - A (ridiculously) small and powerful web framework.