PDF Watermark

The watermark is drawn on top of each selected page as its own layer: either your text, in mid grey at the size and angle you set, or an image you upload. Text is fitted to the page, so a large size is scaled down to stay within about three quarters of the page width instead of running off the edge. Opacity decides how much of the page shows through: low values let the content read clearly through the mark, high values dominate it. It is written into a new copy of the PDF, so your original is untouched.

Where it stops: A watermark is a visual mark, not a security control. It can be removed by anyone determined enough, so it signals status rather than protecting the document: use Protect PDF when the contents need to be restricted. Text watermarks are placed as images, so they cannot be selected or searched, and they are always grey, which does not show up well on dark scanned pages. A heavy watermark across dense text hurts readability, so check a page or two before applying it to a long document.