What do you think about it?
Feedback on the UI or suggestions for improvements or new features would be most welcome.

Looks great - CSV upload is a must, nobody wants to retype all that data. Maybe it's there and I missed it?

Thanks! There is no .CSV upload yet but I think many people have the data in Excel or in Google Sheets. They can just ctrl C + ctrl V them into my spreadsheet user interface.

Which software outputs a .CSV but does not allow table/spreadsheet copying?

I didn't try simple copy paste, for a small number of rows that's probably OK but might get clumsy for larger tables