Watermark PDF
Add a diagonal text watermark such as CONFIDENTIAL or DRAFT to a PDF, without sending it anywhere.
Processed on your device — no upload
How to watermark PDF
- Choose the PDF you want to stamp.
- Type the text, then set its size, strength, colour and angle.
- Press add. The watermarked PDF downloads to your device.
How it works
The watermark is drawn as real text on top of each page's existing content, using one of the fourteen fonts every PDF reader is required to have built in. Nothing is rasterised: the stamp stays crisp at any zoom level, adds almost nothing to the file size, and needs no font file embedded into the document.
Centring rotated text is the fiddly part. A PDF rotates text about its own starting corner rather than its middle, so placing a 45° stamp in the centre of the page means calculating where the rotated bounding box lands and offsetting the start point by half of it. The tool measures the string in the chosen font and size, works out that offset per page, and positions accordingly — which is why the stamp stays centred even when your document mixes portrait and landscape pages.
Strength is a real trade-off, not a style choice. A faint watermark keeps the document readable but is trivial to ignore; a strong one is unmissable but fights with the text underneath. Around 18% is the usual compromise for documents meant to be read, and 35% or more for documents meant to be visibly marked.
All of it runs in your browser. Files people want to mark CONFIDENTIAL are, almost by definition, files they should not be uploading to a stranger's server — so this tool does not have one.
A worked example
You are sending a 24-page commercial proposal to a prospect before the contract is signed, and you want every page marked so it cannot be circulated as a final document.
Choose proposal-v3.pdf. Set the text to DRAFT — NOT FOR CIRCULATION. Because that string is long, drop the size to Small: a long phrase at Large runs past the edges of the page and gets clipped. Leave the angle on Diagonal, which is the shape that reads as a watermark rather than as content.
Keep the strength at Faint and the colour on Grey. Press Add watermark and download: you get proposal-v3-watermarked.pdf and the message Stamped “DRAFT — NOT FOR CIRCULATION” onto 24 pages.
One thing to be clear about: this is a visual mark, not a security control. Anyone with a PDF editor can remove it, and it does not prevent copying, printing or forwarding. It signals status to an honest reader — which is what a watermark is for — and nothing more.
If the document should also carry page numbers before it goes out, number it first and stamp afterwards, so the watermark sits on top.
Questions
Can I stamp a copyright notice or a brand across every page?
Type the text and it is drawn as an overlay on each page. Lower the opacity if it should sit behind the content rather than over it.
Is my document uploaded to add the watermark?
No. The text is drawn onto the pages by JavaScript running in your browser. There is no server behind this site, so the file never leaves your device — which matters especially for documents you are marking as confidential.
Can the watermark be removed by the recipient?
Yes, by anyone with a PDF editor. A watermark communicates status to an honest reader; it is not a security measure and should not be relied on as one.
Why is my watermark cut off at the edges?
The text is longer than the page can hold at that size. Choose a smaller text size, or shorten the phrase. Long strings and the "Large" setting rarely fit together.
Can I use my own colour?
The tool offers grey, red, blue and black. Grey is the conventional choice because it stays legible over both text and images without competing with either.
Does the watermark go behind the text or on top of it?
On top. That is why the strength setting matters: at low opacity the underlying text reads through it clearly, while a strong setting will partly obscure what is beneath.
Does it work on scanned documents?
Yes. The stamp is drawn over whatever the page contains, whether that is text or a scanned image.
Can I watermark only some pages?
Not in this tool — the stamp is applied to every page, which is what a watermark is normally for. To mark a subset, extract those pages with the split tool, watermark them, then merge the document back together.
How much does it add to the file size?
Almost nothing. The watermark is a short text instruction per page in a font the reader already has, so the increase is typically a few kilobytes across the whole document.
Can I watermark PDF files in a batch?
One document at a time. Every page of that document gets the mark, so a 200-page file is a single pass — but watermark PDF files separately if you have several, because the right position and opacity usually differ between them.
Can I watermark PDFs with different text on each?
One document at a time, and that is deliberate rather than a limitation: watermark PDFs separately because the position and opacity that read well on a text page are wrong on a scan, and a batch at fixed settings makes some of them illegible.