What a watermark does and does not do
A watermark is a visual claim. It tells a reader that a document is a draft, a copy, confidential, or belongs to someone. That is genuinely useful: it stops a draft being mistaken for a final version, and it makes an unauthorised copy obviously an unauthorised copy.
What it is not is protection. Anyone with the right software can remove it, and a determined person can simply retype the content. If a document must not be read by the wrong people, encryption and access control are the answer; a watermark is a label, not a lock.
Choosing the settings
- Opacity is the setting that matters most. Around 15 to 25 percent is usually enough to be unmistakable while leaving the text underneath comfortable to read. Above 40 percent the document becomes tiring.
- Diagonal placement is the convention for status marks such as DRAFT or CONFIDENTIAL, partly because it is harder to crop out than a corner mark.
- Tiled placement repeats the text across the page. It is more intrusive and harder to remove cleanly, which makes it suited to documents being circulated widely.
- Colour matters less than opacity. A mid grey or a muted warm tone reads as a mark rather than as content, which is what you want.
Common wording
DRAFT, CONFIDENTIAL, COPY, SAMPLE, NOT FOR DISTRIBUTION and INTERNAL USE ONLY cover most needs. Adding a date or a recipient's name is worth considering when a document is sent to several parties, because it makes a leaked copy traceable to the version it came from.
Order of operations
Watermark last. If you intend to merge several documents or extract pages, do that first and apply the mark to the finished file — otherwise the watermark can end up on some pages and not others. If you also plan to compress, watermark first, since compression flattens pages into images.
Frequently asked questions
Is a watermark a form of security?
No. It is a visual label. It communicates status or ownership clearly, but it can be removed with the right software and does not restrict who can open or read the document.
What opacity should I use?
Around 15 to 25 percent is usually right — clearly visible without making the underlying text hard to read. Above 40 percent most documents become uncomfortable.
Does the watermark cover the text underneath?
It is drawn on top, but at a low opacity the content stays readable. The document text also remains selectable, since the watermark is added as real text rather than flattening the page.
Can I watermark only some pages?
This tool marks every page. To mark a subset, extract those pages with the split tool first, watermark them, then merge the document back together.
Is my document uploaded anywhere?
No. The PDF is opened and rewritten in your browser, which matters for exactly the kind of document people tend to watermark.