CSSBattle - Play against others in golf with your CSS skills
AlgoExpert.io - A better way to prep for tech interviews
Indie Maker The Game - Open source game about indie makers
Interview Cake - Free practice programming interview questions. Interview Cake helps you prep for interviews to land offers at companies like Google and Facebook.
Gamefroot - Gamefroot is the fun way to make games, animations, stories and share them with the world.
interviewing.io - Free, anonymous technical interview practice