Upload the PDF, type the watermark text, and click Add watermark - the download stamps that text diagonally across every page in a gray, semi-transparent style.
Need another quick PDF fix? To turn sideways pages upright, see rotate PDF.
Add Watermark to PDF
Add Watermark to PDF stamps one diagonal text watermark across every page of a PDF. The whole watermarking pass runs on your device in this tab; the PDF never leaves the browser or reaches a server.
Key features
- The same watermark text is stamped on every page of a multi-page PDF in one pass - no repeated uploads or per-page steps.
- The watermark text size adjusts automatically to fit each page's width, so the same text stays readable whether the PDF is portrait or landscape, letter or A4.
- Does not support custom position, color, or size, image watermarks, or a different watermark per page.
Compared with a desktop app or an upload-based service
Three common ways to stamp a watermark on a PDF are a browser-based tool like this one, a desktop application, or an upload-based online service. They differ in where your file goes and what you have to install first.
| Aspect | Add Watermark to PDF (this tool) | Desktop application | Upload-based online service |
|---|---|---|---|
| Where your file goes | Stays on this device | Stays on this device | Uploaded to a server |
| Install required | No | Yes | No |
| Works without an account | Yes | Yes | Varies by service |
Exactly how the stamp is sized and placed
Add Watermark to PDF starts every stamp at 48pt and shrinks it in 2pt steps, down to a floor of 8pt, until the text fits inside 70% of that specific page's width. Because that check runs separately per page, the same watermark text can come out at different sizes across one PDF - full size on a wide landscape page, smaller on a narrow portrait page next to it. The font itself is a fixed Helvetica Bold, and the stamp is always drawn at a 45-degree angle, 35% opacity, in a fixed gray tone, centered on both the horizontal and vertical middle of the page - none of those five values (font, angle, opacity, color, or position) can be changed from the page.
The watermark text field accepts up to 60 characters; the field itself refuses to accept more, so there is no separate length warning to watch for. Add Watermark to PDF also saves the finished file using the same object-stream re-save pdf-lib step this site's separate PDF compress tool uses, so a watermarked download often comes out a little smaller than a plain re-save of the same source file, even though this tool does not report a size change the way the compress tool does. The download is always named watermarked.pdf, whatever the source file was called.
Frequently Asked Questions
What does Add Watermark to PDF do?
Add a watermark to every page of a PDF, right in the browser.
When should I reach for add watermark to pdf?
Applies one fixed diagonal text style (gray, semi-transparent, centered) - does not support custom position, color, size, image watermarks, or a different watermark per page.
What complementary tools work well alongside add watermark to pdf?
To split, merge, rotate, or delete pages from the PDF instead, see the related-tools section.
Can I watermark a PDF that has a password on it?
A PDF with owner or permission restrictions but no password required just to open it still loads and gets watermarked normally. A PDF that needs a password before it will even open fails to load, and the tool shows "Could not process the PDF" instead of a blank or frozen page.
Is there a limit on how long the watermark text can be?
Yes - the watermark text field has a 60-character cap built into the field itself, so it simply stops accepting more typing past that length rather than truncating the text afterward.
What happens if I click Add watermark without typing any text?
Nothing is processed. The tool shows "Type the watermark text first." and the PDF you already chose stays selected, so you only need to type the text and click again.
Does adding a watermark make the PDF file bigger?
Not necessarily. The save step uses the same object-stream re-save this site's PDF compress tool relies on, so a watermarked file sometimes comes out a little smaller than a plain copy of the source PDF, even though this tool does not display a size comparison for the watermark step itself.