Free web tool
Watermark a PDF
Stamp CONFIDENTIAL, DRAFT, or any text you like across every page — diagonal, centred, or as a small footer. Control the opacity and size, and keep the whole thing on your own machine.
The short answer
To watermark a PDF, open it in a watermarking tool, type the text you want stamped (such as CONFIDENTIAL or DRAFT), choose its placement and opacity, and download the new file. The text is drawn into each page's content, so it shows in every viewer and prints with the document.
How this works
Add your PDF
Drag it in or click to browse. The file is read locally — no upload at any point.
Set the text and style
Type your own text or tap a preset like CONFIDENTIAL. Choose diagonal, centred, or footer placement, then set the opacity and size.
Download
Every page is stamped and the new PDF is handed back to you immediately.
Why on-device matters here
The word you are stamping is usually CONFIDENTIAL — which makes uploading the document to an unknown server to add it faintly absurd. Everything here happens in your browser.
This tool does the work in your browser with pdf-lib. Your file is read into memory, edited, and handed back — no request ever carries it off your machine. Open your browser's Network tab if you want to verify that yourself.
Frequently asked questions
How do I put CONFIDENTIAL across a PDF?
Drop the file in, tap the CONFIDENTIAL preset (or type your own wording), pick diagonal placement, and download. Around 15-20% opacity is the usual choice — visible enough to be unmistakable, faint enough to read the document through.
Can the watermark be removed by the recipient?
Yes, with effort. The text is drawn into the page content, so it is not trivially deletable in a reader — but anyone with a PDF editor can remove drawn objects. A watermark communicates status and deters casual reuse; it is not a security control and should not be relied on as one.
What opacity should I use?
15-25% works for most documents. Below 10% it can vanish on busy pages or when printed on a low-toner printer; above 40% it starts fighting the text underneath. If the document will be printed, err slightly darker than looks right on screen.
Does the watermark go on every page?
Yes, every page in the document gets the same stamp. If you need it on only some pages, split the PDF first, watermark the part that needs it, then merge the pieces back together.
Can I use an image or logo as the watermark?
Not in this tool — it stamps text only. An image watermark needs the logo embedded and scaled per page size, which is a different job. Text covers the common cases: CONFIDENTIAL, DRAFT, COPY, SAMPLE, a matter reference, or a recipient name.
Will the watermark print?
Yes. It is part of the page content rather than a viewer annotation, so it prints and appears in any reader, on any device.
Why is my long watermark running off the page?
The font size is fixed rather than auto-fitted, so a long phrase at a large size can overrun the page. Shorten the text or reduce the size — around 52pt suits a single word diagonally on A4, and much less for a full sentence.
Does my PDF get uploaded to a server?
No. The watermark is applied in your browser tab with pdf-lib. Given the documents that typically get stamped CONFIDENTIAL, uploading them to a stranger's server to add that word would be self-defeating.
Can I watermark a password-protected PDF?
Not here. Encrypted PDFs are rejected with a clear message rather than producing broken output. Remove the password first in Preview (macOS) or Adobe Reader.
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