Now UI Kit - A beautiful Bootstrap 4 UI kit. Yours free.
One Click Test - Tool for quickly testing your design layout in one click.
UX Toolkit for Figma - Create beautiful user flow charts, sitemaps and wireframes
W3C Mobile Checker - Make websites work better on mobile devices
Landing UI Kit - Handcrafted UI components for landing pages
Flexbox Grid - Grid based on CSS3 flexbox