Save modified PDF on server
A: There are 2 ways you can do this:
Save the whole PDF: You can export the modified PDF as an arrayBuffer using
Instance#exportPDF. Then you can convert this arrayBuffer to blob and sent it to your server. You can see an example in the Sending the PDF to a server section.
Save the changes only: If you just want to save the changes made by the user on the original PDF, you can use
Instance#exportInstantJSONto export a JSON containing all the changes. You can store this separately and apply it when you load the original PDF next time using
Configuration#instantJSON. With this approach you won’t have to repeatedly save the PDF file and you can use the original PDF everytime.