Befront - Learn UX/UI design skills in practice with bite-sized tasks
UX Challenges - Done reading about UX? Start doing it.
Hyper - Extensible, cross-platform terminal built on open web standards.
Uxcel - The easiest way to learn UX/UI design
VUIchallenge - Daily challenges to improve your voice design skills
uxtoast: Learn UX Design - Become familiar with design laws and learn how to use them.