Interesting post. Personally, while making the website fully open-source could enhance security IF more people find issues with the website, I do believe that people would not care so much about the source code (web app logic or whatever else KA has not made available yet) as much as learning (which is fine), and that more bad actors would attempt to exploit any security issues to potentially get PII. That's my 2 cents.

And holy that is a lot of repos!

I agree that the vast majority of people using Khan Academy don’t care about the source code. However, if the source code is made available to people like me who are actually interested in creating an educational system around the Khan academy philosophy by exploiting Khan Academy’s great features, then the people we reach (hopefully, many) will benefit greatly. I think making the code available would only help to accelerate the coming into being of Sal Khan’s vision of the future of education (which, incidentally, is laid out beautifully in his book “The One World Schoolhouse”) by allowing educators around the world to customize the site to their own needs.

Also, regarding security issues, I think the benefits far outweigh the costs. I’m sure they can hire competent software engineers to deal with this…