Putting a PDF into the URL is not entirely impossible, but comes with serious limitations %)

I guess the PDF wouldn't have to be stored in the application/URL? Just a tool to load it, fill+annotate+sign it and export back to disk.

	▲	nine_k 44 minutes ago \| parent [-]
		The specialty of all apps here is that the entire document is in the URL. It's a great idea, but this limits the size of the serialized document to 2048 kiB for Chrome, and 64 kiB for Firefox.