Chosen is a library for making long, unwieldy select boxes more friendly.
Full-sized drag & drop event calendar (jQuery plugin)
Lightweight, robust, elegant syntax highlighting. A spin-off project from Dabblet.
LoopBack makes it easy to build modern applications that require complex integrations.
Semantic empowers designers and developers by creating a shared vocabulary for UI.
Medium.com WYSIWYG editor clone.
The official jQuery user interface library.
Reactive libraries for Angular
jQuery Validation Plugin