Signing without your document ever leaving the tab
Signing a PDF involves rendering the page, capturing a drawn or typed signature, and flattening it into the document — all of which is straightforward to do with the file held in browser memory rather than sent to a server. There's no step in that process that structurally needs a remote backend.
PrivaPDF's sign tool works exactly that way: the PDF is read locally, your signature is composited onto it locally, and the signed file is handed back for download — verifiable in DevTools' Network tab, where you'll see no request carrying the document's content.