Edit pdf form in a webapp [closed]

in my webapp (.NET/blazor stack but not matter the problem is general), i would like to allow my users to edit directly pdf (edit the form inside the pdf) stored on the server.

I allow this for word/excel file with webdav protocol and it work perfectly

For pdf forms, i found nothing similar. the built-in pdf viewer in chrome dont seem let me save the pdf directly on the server (precision, i target specifically chrome).

I tried also open the file directly on the server with adobe acrobat reader but kind of same, the save failed for write permission (which i can understand)

so I don’t know what can be my solutions now. I see many JS pdf editor library but there all look expensive and with a ton of feature i dont need. i would only like allow the user fill the forms through the webapp and save it on the server.

I wait for your suggestions

Thanks !