Not sure if this has changed in the last few years, but Khan Academy heavily invested in App Engine: http://highscalability.com/blog/2013/4/1/khan-academy-check

Not sure if this has changed in the last few years, but Khan Academy heavily invested in App Engine: http://highscalability.com/blog/2013/4/1/khan-academy-checkbook-scaling-to-6-million-users-a-month-on.html http://highscalability.com/blog/2013/4/1/khan-academy-checkb...