We're a non-profit with a mission to provide a free, world-class education to anyone, anywhere. It's a big mission that we're taking on step by step. While we want anyone to be able to get a great education independently, we've been focusing a lot on trying to help teachers working in their classrooms (and a lot of teachers and parents are using Khan away from their classrooms right now!)
Our site has been built on Python 2 and Google App Engine for its first 10 years of existence. We're now in the midst of a rebuild in Go (still on App Engine).[1] Parts of that new Go-based infrastructure are already running in production.
To say that this is an exciting time for us would be an understatement, I think, but we continue to have working sustainably as an engineering principle. (Our principles are available publicly[2].)
[1]: http://engineering.khanacademy.org/posts/goliath.htm [2]: https://docs.google.com/presentation/d/1ZQ-HTuH38L8sf4ZObfJN...
For me this is a major factor in choosing an employer so I followed your link ([2]) but did not see anything in your principles that refers to working sustainably or work-life balance, etc.
The engineering principles take our overall organization values and lay out engineering-specific takes on them. I haven't seen the organization values posted publicly, but one of the top line values is "Work responsibly and sustainably" and I can say firsthand that this is something we talk about in management meetings.