Add a Watermark to a PDF
Stamp a word across every page of a PDF. Set the text, the angle and how strong it looks, and watch it land on a real page of your own document before you build anything. The text underneath stays selectable, and nothing is uploaded.
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The pages
Load a PDF to see its pages.
Your PDF never leaves this device.The file is opened by your browser, the marked document is built here in the page, and the download comes from your own machine. The file you dropped in is not modified.
Sized against what the reader sees
A page carries its own rotation, so an A4 sheet sitting at ninety degrees is displayed as landscape even though its stored dimensions say portrait. The mark is measured against what the reader actually sees, which is why a document of mixed pages comes back looking consistent rather than with one page stamped sideways.
How to use this tool
Drop a PDF on the box at the top. Every page appears with the mark already drawn on it, using your own document rather than a mock up, so what you see is what you will get.
Change the text, the angle, the strength or the colour and the pages redraw as you go. When it looks right, build the file.
A watermark is a label, not security
Worth saying before anything else, because it is the thing people get wrong about watermarks.
The mark is drawn onto the page as an ordinary object. Anyone with the right software can take it off again, and no watermark tool anywhere can change that, whatever it claims. Stamping a drawing NOT FOR CONSTRUCTION is useful because it tells an honest reader what they are holding. It will not stop a determined one.
If a document genuinely must not be altered, the answer is a password or a signature, not a watermark.
Sized against what the reader sees
The size is not fixed. It is worked out for each page so the text fits at the angle you chose, which is why a landscape sheet and a portrait one in the same document end up with different numbers and still look right.
The part that catches software out is that a page carries its own rotation. An A4 sheet stored as portrait but displayed at ninety degrees is landscape as far as the reader is concerned. Measuring the stored dimensions instead puts the mark off centre and, for a straight across mark on A4, about forty per cent smaller than it should be.
So every page is measured as displayed, and the mark is mapped back into the page coordinates afterwards. A drawing set with a mixture of orientations comes back looking consistent.
A worked check you can repeat
Stamp CONFIDENTIAL diagonally across a document containing an A4 portrait page, a Letter page, an A4 page rotated to landscape and a genuine A4 landscape page. All four are marked, none overflows, and the rotated page gets exactly the same size as the real landscape one.
A forty five degree diagonal is limited by the shorter side of the page whichever way round it is, so portrait and landscape give the same size for it. A straight across mark is larger on landscape, because there is more width to fill.
The placement was checked against an independent implementation before publishing: fifty six hand written cases covering every position, all four page rotations, mixed paper sizes and the clamping of strength and coverage. Then fifty thousand generated placements across seven paper sizes, every angle from zero to three hundred and fifty nine, and coverage from a fifth of the page to nearly all of it, confirming that the mark never leaves the page and never shrinks below readable. Twenty thousand of those were repeated against the copy running here in the browser.
Mistakes that catch people out
Treating it as protection. It is a label. Use a password if the document must not be altered.
Setting the strength too high. Anything above about forty percent starts to fight the text underneath. Twenty five is usually enough to read at a glance.
Tiling when once is enough. A tiled mark is harder to ignore and much harder to read through. Save it for documents that really must not be mistaken for the issued version.
Expecting the same size on every page. A mixed document gets different sizes on purpose, so the mark sits properly on each one.
Assuming a password protected file will open. It will not. Remove the protection first, in software that has the password.
Common questions
Is my PDF uploaded anywhere?
No. The file is opened by your browser, the marked document is built here on the page, and the download comes from your machine. Nothing crosses the network.
Can the watermark be removed afterwards?
Yes, by anyone with the right software. A watermark drawn on a page is an object like any other, so treat it as a label rather than as security.
Does the text underneath stay selectable?
Yes. The mark is drawn onto the page rather than flattening it into a picture, so the document stays searchable and you can still copy from it.
Why is the size different on some pages?
Because the size is worked out to fit each page at the angle you chose. A landscape page and a portrait one need different sizes for the same text to sit properly.
What happens on a page that is already rotated?
It is measured as the reader sees it. An A4 page sitting at ninety degrees is treated as landscape, so a mixed document comes back looking consistent.
Can I mark only some pages?
Yes. Type a list in the pages field, such as 1-5 or odd. Every other page is left completely untouched.
Related PDF tools and reference
Reference: ISO 32000, the standard that defines page content and the rotation value used here.