This tool opens a Word document in your browser so you can read it without Office, and then lets you put things on top of it: a scanned signature, a stamp, a logo, a redaction box, or a line of text. It is meant for the small jobs that usually force you to open Word — signing a contract you were sent, marking up a form, adding a note to a page before passing it on. The document is read on your device and rendered in the page, and what you place on top is saved into a PDF. The original .docx is never modified and never uploaded.
No. The .docx is opened with your browser's file API and rendered in the page, and the PDF is assembled in memory before it is saved to your device. Nothing is sent over the network, so the tool also keeps working once the page has loaded and you go offline.
No. The .docx on your device is left exactly as it was. What you place on top lives only in the page until you save, and then it is written into a new PDF. If you need an edited .docx, you still need Word or a word processor.
No. Only the .docx package used by Word 2007 and later can be read in a browser; the older binary .doc format cannot. Opening the file in Word or Google Docs once and saving it as .docx makes it readable here.
A .docx does not store pages — Word works out where each page breaks when it opens the file, using the fonts installed on that machine. The viewer does the same job with the fonts your browser has, so line breaks and page breaks can land in slightly different places, especially with unusual fonts or complex tables.
Not the document's own text. You can add your own text boxes on top of it, which covers the common cases — filling a blank, correcting a line, adding a note — but rewriting a paragraph in place would mean editing and saving the .docx, which this tool deliberately does not do.
A signature photographed or scanned as a PNG with a transparent background, a company seal, a logo on a letterhead, a QR code, or a solid rectangle used to cover something that should not be readable in the copy you hand out.