Codecademy, from Skillsoft, helps millions of learners create inspiring careers in technology through an interactive online platform and a growing catalog of courses, skill paths, and career paths.

Real Dev is a platform to challenge developers with real-life coding tasks. It's a platform to learn backend and frontend projects by doing. It's also a recruiting assessment tool for business to hire engineers with practical skills.

Devhints is a set of useful cheatsheets displayed in a stylish way

hackattic is an attempt to show people that programming challenges right now are DULL, lack creativity and are a sad way to estimate someone's skills. It's a very, very early phase, hacked up over a few lazy weekends, which the simple intention of making step zero out of possibly many to come.