Colaboratory - Free Jupyter notebook environment in the cloud.
Habit List - Create good habits and break bad ones with the app that keeps you focused.
Numerai - Hedge fund that crowdsources market trading from AI programmers over the Internet
Momentum - Agile goal and performance management
Infosec Skills - Infosec Skills is technical expertise and engineering development knowledge-building platform where engineers and technical experts can come together to share and learn about the latest security development techniques and strategies.
Habitica - Habitica is a free habit building and productivity application.