How to make an Excel masive upload?

I just need to setup a masive upload with excel so the user can create many “things” with one upload.
Would be great with Excel instead of CSV.

Is there any documentation?

Why not export Excel as CSV? Excel is just CSV with extra steps (I simplify…).

You could convert an excel file to CSV when it’s uploaded and then process the resulting CSV.

Thank’s for your reply. I know, but for the UX it’s better to just use .xlsx (normal Excel) cause it’s easier for the user.

Anyway, CSV would be a good option if it’s not possible with .xlsx.