hackattic - No nonsense, real world programming challenges
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Codewars - Achieve code mastery through challenge.
Cvent - Cvent's event management software provides event planners with a complete solution to increase event attendance and decrease event costs.
Real Dev - Real-life coding skill challenge
Ticket Tailor - Ticket Tailor is an easy-to-use event ticketing platform that allows event organizers of all shapes and sizes to sell tickets online.