Khan Academy is an American non-profit educational organization created in 2008 by Salman Khan, with the goal of creating a set of online tools that help educate students. The organization produces short lessons in the form of videos. Its website also includes supplementary practice exercises and materials for educators. All resources are available for free to users of the website and app.
Account there is more for saving your progress, not gathering your data. So I think it worth 5 bars, besides that you can have access to the courses without account
It seems that KhanAcademy does not force you to have an account in order to access their courses, but you need an account to save your progress and get “personalized help”. Overall it seems to be quite trade-free.
Khan Academy requires you to create an account, but once you have that, you have access to all courses of that platform.