A watermark answers a question the reader would otherwise have to ask: is this the final version, and am I allowed to pass it on. Stamping DRAFT across a proposal or CONFIDENTIAL across a set of figures costs nothing and saves the awkward conversation later. This tool draws your text across every page of a PDF and gives you the file back.

It all happens in your browser. The document is read, marked and saved on your own machine, so nothing about it reaches a server.

Choosing the text

Short words work best. DRAFT, CONFIDENTIAL, SAMPLE, NOT FOR CIRCULATION and a client name are the usual choices, and all of them read clearly at a large size across the middle of a page. A long sentence has to be set small to fit, at which point it stops working as a watermark and starts looking like a footnote.

Text is drawn in Helvetica Bold. There is no second font to pick, which keeps the output predictable across readers and printers.

Size, opacity and angle

Opacity is the setting that decides whether the document is still usable. Around ten to twenty per cent leaves a mark that is unmistakable on screen and still lets the text underneath be read. Push it past forty and the page becomes hard work. Very low values may vanish on a printer that dithers light greys, so test a page if the file is going to be printed.

Size and angle change how much of the page the mark covers. Diagonal is the traditional choice because a tilted line crosses more of the page and is harder to crop out of a screenshot. Horizontal suits a short word on a dense page, where a diagonal line would cut through too many rows of text.

Where the mark lands

The watermark is centred on each page, measured from that page's own dimensions. A file mixing A4 and A3 pages, or portrait and landscape, gets a correctly centred mark on each one.

Pages carrying a rotation instruction, which most scanned documents do, are handled in the orientation you see on screen. The mark sits in the middle of the page as displayed and runs at the angle you chose, not at an angle inherited from how the scanner stored it.

What a watermark is and is not

A watermark is a visible label. It tells an honest reader what they are holding and makes a leaked screenshot traceable back to a version. It is not a lock. The text is ordinary page content, and anyone determined enough can strip it with the right software.

For control over what a reader can do with a file, look at a password or permissions instead. The two work well together: a watermark states the status, a password limits access.

Frequently asked questions