Android Nougat GUI - Free fully customizable Android UI Kit for Sketch
Now UI Kit - A beautiful Bootstrap 4 UI kit. Yours free.
Contra Wireframe Kit - Open source wireframe kit for design and prototyping 🚀
UX Toolkit for Figma - Create beautiful user flow charts, sitemaps and wireframes
Epic Pxls - UI kits, icons, templates, mockups and more, free
Landing UI Kit - Handcrafted UI components for landing pages