Uxcel - The easiest way to learn UX/UI design
Maze - Beautiful & actionable analytics for InVision prototypes
uxtoast: Learn UX Design - Become familiar with design laws and learn how to use them.
ProtoPie - ProtoPie is the easiest tool used to turn your UI/UX design ideas into highly interactive prototypes for mobile, desktop, web, all the way to IoT.
Awwwards Academy - Leading thinkers teach digital talent on awwwards academy
W3C Mobile Checker - Make websites work better on mobile devices