I want to embed a fillable PDF file in HTML, have the user fill in the PDF (on the website to be seamless inside our service) and then upload the filled in PDF file to my backend.

I can't change the PDF itself, as it's a standardised document from a third party.

<embed id="pdfObject" src="link-to-pdf.com" type="application/pdf"></embed>

How can I use Javascript to access the modified PDF? I'd like to have an upload button, that uploads the modified PDF.

Thanks for your help!