Add a Watermark to a PDF
Stamp a text watermark like DRAFT or CONFIDENTIAL diagonally across every page of a PDF, with control over size, opacity, color, and angle — all in your browser.
FreeNo sign-upPrivate — runs in your browser, nothing is uploaded
Drop a PDF here, or browse
One PDF · processed in your browser, never uploaded
Runs entirely in your browser — your file is never uploaded to a server.
Quick answer
To watermark a PDF, upload it, type your watermark text (for example CONFIDENTIAL or DRAFT), and set the size, opacity, color, and rotation; the tool stamps it diagonally across the center of every page and downloads the result. It runs entirely in your browser with pdf-lib, so the document is never uploaded, and the text stays crisp because it's drawn as real PDF text, not an image.
Formula & method
The tool embeds the Helvetica-Bold font and draws your text on each page at the chosen size, color, and opacity, rotated to your angle and positioned so it runs diagonally through the page center. Because it's rendered as native PDF text, the watermark stays sharp at any zoom and adds very little to the file size.
Examples
- Input
- CONFIDENTIAL, 50pt, 30% opacity, 45°
- Result
- Diagonal red watermark
- Why
- A classic semi-transparent diagonal mark across every page.
- Input
- DRAFT, 60pt
- Result
- Large DRAFT on each page
- Why
- Bigger text makes the status unmistakable.
- Input
- yourcompany.com, 24pt, 15%
- Result
- Faint diagonal label
- Why
- Low opacity keeps the document readable while marking ownership.
When to use this tool
- Marking a document as Draft, Confidential, or Sample before sharing.
- Branding a PDF with your name or site across every page.
- Discouraging unauthorized reuse of a document.
Common mistakes
- Setting opacity to 100%, which can obscure the underlying text and make pages hard to read.
- Using a very long watermark string that runs off the edges of smaller pages.
- Expecting the watermark to be un-removable — like any overlay, a determined editor can strip it.
Frequently asked questions
How do I watermark a PDF?
Upload it, type your watermark text, set the size, opacity, color, and angle, then click Add watermark. The stamped PDF downloads.
Does the watermark go on every page?
Yes. The text is stamped diagonally across the center of all pages in the document.
Is my PDF uploaded?
No. The watermark is applied locally in your browser with pdf-lib; the file stays on your device.
Will the watermark blur when zoomed?
No. It's drawn as real PDF text, so it stays sharp at any zoom level and keeps the file small.
Can I use an image as the watermark?
This tool stamps text. For an image watermark, place the logo on each page with a full PDF editor.
Can the watermark be removed?
No overlay is truly permanent — a determined user with the right software could remove it — but it clearly marks status and ownership for normal use.
Sources & references
External references open in a new tab. We are independent and not affiliated with these organizations.
- ✓ Free to use
- ✓ No sign-up required
- ✓ Runs entirely in your browser — nothing is uploaded.
- ✓ Formula and method shown above
Provided “as is” for general information only — results may be inaccurate, so verify before you rely on them. No warranty; use at your own risk.
Built and reviewed by HIFreeTools against the formula shown above and any authoritative references cited on this page. See our methodology and editorial standards.
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Embed this tool on your site
Free to embed, no sign-up. Paste this code where you want the watermark pdf to appear: