Runs on your device · Your file never leaves your device.
Stamp text across your pages — DRAFT, CONFIDENTIAL, a company name — with control over colour, size, rotation and opacity. Apply it to every page or only the ones you select.
The watermark is drawn into the page content, so it travels with the file and appears when it is printed or opened anywhere. It is a deterrent and a label, not a security control: anyone determined can still remove it.
Because the stamping happens on your device, a confidential document does not have to be uploaded to a stranger’s server just to be marked confidential.
Not for: Security — a watermark deters casual reuse, it does not lock or encrypt the document.
The text is written once on each page, as a single bold line centred on the visible page. It starts as CONFIDENTIAL in grey, at 48 points, 20% opacity and 45 degrees. Size runs from 8 to 200 points, opacity from 5% to 100% in steps of 5, and the angle from -90 to 90 degrees in steps of 15; positive angles rise from left to right.
If the slanted line would take more than 90% of the page, across or from top to bottom, it is made smaller until it fits. On an A4 portrait page, CONFIDENTIAL at 45 degrees therefore stops growing at about 90 points whatever larger size you type, and at 90 degrees a long word is reduced to fit the height of the page.
Text made only of western European letters, digits and common punctuation is drawn with the built-in Helvetica Bold font. Anything else is drawn with fonts served from this site and loaded the first time they are needed: every other Latin letter, including Turkish ğ, ş, ı and İ and Polish and Czech letters, Greek, Cyrillic, Hebrew, Arabic, Persian, Urdu, Hindi, Bangla, and the 6,763 common Chinese characters of the GB2312 set.
Right-to-left text is laid out right to left, and one line can mix scripts, as in CONFIDENTIAL — سري. A character with no font here, such as Japanese kana or a rare Chinese character, is named in a message and the watermark is not applied, so a page never comes out with letters missing.
The watermark is drawn on top of the page content, not behind it. At low opacity the text beneath shows through; a dark colour at high opacity can hide it. With Selected pages under Apply to, only the pages you pick are marked. A page turned by a rotation setting shows the angle you chose as you see the page, and a page whose margins were trimmed gets the watermark centred on the part you can see.
To make the mark harder to remove, run the result through /flatten-pdf with Everything selected, which turns each page into a picture. The cost is that the text of the page can no longer be selected or searched.
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