Watermark PDF — Add a Text Watermark in Your Browser
Stamp a word across every page of a PDF — DRAFT on a contract that is not final, CONFIDENTIAL on a board pack, a client name on a proof. You control the text, the angle, the size, the colour and how see-through it is, and you can watch it land on the real page before you save anything. The file is opened and rewritten inside your browser, so nothing is uploaded.
The big names in this corner of the web — Smallpdf, Sejda, iLovePDF, PDF24 — all send the document to a server first. For a marketing PDF that is fine. For an unsigned agreement, a salary letter, or anything covered by an NDA, it means handing a copy to a company you have no relationship with. This page does the same job with pdf-lib running on your own machine, so the document is never transmitted anywhere.
A watermark is a deterrent, not a lock
Text drawn on top of a page can be removed by anyone with the right software, and a screenshot ignores it entirely. What a watermark does well is make the status of a document obvious at a glance and make casual re-use awkward — a printed page marked DRAFT is hard to pass off as final. If you need the content itself to be unreadable, redact it; if you need to stop people opening the file, add a password.
Settings that actually read well
A single diagonal stamp at 45 degrees, around 60 to 70 points, at 15 to 25 percent opacity is the combination most people are picturing. Tiling the text across the page is stronger, and worth it when the document may be photographed or reproduced, but it makes body text harder to read — drop the opacity to around 10 percent if you tile. Grey reproduces more predictably than red on a black and white printer. The multiply blend keeps the page text legible through the stamp instead of laying a flat block of colour over it.
Pages that are not upright
Scanned documents often carry a rotation flag, so page four can be stored sideways even though it looks upright on screen. The stamp is positioned in the orientation you are looking at and then mapped back into the page’s own coordinates, which is why the text lands square on rotated and landscape pages instead of running off the edge.
Related: add page numbers, apply Bates numbers to a set of files, or watermark an image instead.
How to use Watermark PDF
- Drop the PDF onto the page. It is read in your browser — no upload, no queue, no account.
- Type the watermark text, or tap one of the presets such as DRAFT or CONFIDENTIAL.
- Choose one stamp in the centre or a tiled pattern, then set the size, angle, colour and opacity while watching the preview.
- Turn the pages to check how the stamp sits over a busy page as well as a sparse one.
- Click Add Watermark & Download. The original file on your disk is untouched; you get a new copy.
Features
- Live preview on your own pages — the real first page, rendered, with the stamp where it will actually land.
- Centre or tiled — one mark for a status label, a repeating pattern for anything likely to be copied.
- Full control of the look — text, size, angle from -90° to 90°, any colour, and opacity from 5 to 100 percent.
- Multiply blend — the page stays readable underneath instead of disappearing behind a block of colour.
- Rotated and landscape pages handled — the stamp is placed the way the reader sees the page.
- Nothing leaves your device — the PDF is parsed and rewritten locally, so confidential drafts stay confidential.
Frequently Asked Questions
Is the document uploaded anywhere?
No. The PDF is read into memory in your browser, edited with pdf-lib, and saved straight back to your downloads folder. Nothing is transmitted, which is the main reason to use this rather than a server-based watermark service for anything sensitive.
Can someone remove the watermark afterwards?
Yes, with effort. The text is drawn as real content on the page, so a PDF editor can select and delete it. A watermark marks a document’s status and discourages casual re-use; it is not a security control. For content that must not be readable, use Redact PDF, which removes the text rather than covering it.
What opacity should I use?
Around 15 to 25 percent for a single diagonal stamp, and nearer 10 percent if you tile the text, because a repeating pattern covers far more of the page. Above 40 percent the body text becomes difficult to read on screen and worse in print.
Can I put an image or logo watermark on a PDF?
This page handles text only. To place a logo, add it as an image with the PDF editor, or watermark the underlying images before they go into the document using Watermark Image.
Does it work on a password-protected PDF?
Not while it is locked. Remove the protection first with Unlock PDF — which needs the password — and then watermark the unlocked copy.
Why does my watermark look different on one page?
Pages inside one PDF can have different sizes and rotation flags, which is common in scanned or merged documents. The stamp is sized in points and centred on each page individually, so a landscape page shows the same text across a wider area. Step through the preview to check the unusual pages.
Is there a page or file-size limit?
No enforced limit, but the whole file is held in memory, so very large documents depend on your device. Files up to about 100 MB are comfortable on a normal laptop; a phone will struggle sooner.