[zeptomu]

Interesting comparison and so far there does not seem to be a clear winner in this space - although there clearly is demand ("web shell for scientific work in a managed Linux environment").

At the moment CoCalc is my favorite, although I would prefer a slightly less cluttered user interface and less features (the distinction between Jupyter and Sage notebooks can be confusing - which is mostly historic as Sage built the groundwork, but Jupyter notebooks got more popular).