Microsoft Word / Excel Simultaneous teamwork... How?

Hello!
I would look for a solution like the one Microsoft Office Online uses.
So if you have say an Excel file, it can be opened by 2 users at once to edit …
If one writes something in it, the other can see it.

Is there such an additional application?
Microsoft Office Online has been discarded

Thank you very much

ONLYOFFICE and Collabora both have collaborative editing.

Thanks…

With this option if I open a file in Microsoft Excel, can anyone else open and edit it?

or it only works with Onlyoffice’s own excel editor

Yes, it will work. You can create a spreadsheet with Excel store it on Nextcloud and update it with OnlyOffice. We do it every day.

I open a file in Microsoft Excel, can anyone else open and edit it?

Only if you close your local Excel and only use Collabora or OnlyOffice.

understand! so then there is no way to edit the same document with 2 microsoft excels.
only if they use Collabora or OnlyOffice?

That is correct. For collaborative editing, they must all use ONLYOFFICE/Collabora (not both). Anyone opening the file in MS Excel locally would not be participating and would overwrite the file on save.