Last updated 28 August 2026
A watermark is a label, not a lock
Stamping DRAFT or CONFIDENTIAL across a document does a useful job: it tells anyone who opens it, or finds a printout on a desk, what they are looking at and how much to trust it. What it does not do is prevent anything. The text is drawn as a layer in the PDF and can be deleted by anyone with a proper PDF editor in about ten seconds. That is worth knowing before relying on it for anything sensitive — if a document genuinely must not be redistributed, watermarking is not the control you need. Opacity is the setting people most often get wrong: low enough to read the content through it, high enough that a photocopy still shows it. Somewhere between fifteen and twenty-five percent usually satisfies both, and tiled mode is worth using when the concern is someone cropping a screenshot around the mark.
Common questions
Can the watermark be removed?
Yes, easily, by anyone with a PDF editor. It is drawn as a layer rather than burned into the page content. Watermarking labels a document, it does not secure it — if redistribution genuinely matters, this is not the right control.
What opacity should I use?
Between fifteen and twenty-five percent usually works: light enough to read the document through, dark enough to survive being printed or photocopied. Higher than about forty percent starts making the text underneath hard to read.
What does tiled mode do?
It repeats the watermark in a grid across the whole page rather than placing one diagonal mark in the centre. It is harder to crop around, which matters if you are worried about screenshots of part of a page.
Is my file uploaded?
No. The PDF is opened, stamped and saved entirely in your browser. Nothing is sent to a server.