Watermark PDF
Stamp CONFIDENTIAL, DRAFT, your name or your logo across a PDF. Set the opacity, angle and position, tile it over the whole page, choose which pages get it and download the result. The PDF stays on your device.
Standard PDF fonts only support Latin characters. Unsupported characters will be removed.
Transparent PNG logos give the cleanest result.
Over the content is always visible. Behind the content looks like a print underlay, but it is hidden on scanned pages or pages with a solid white background.
How to use the Watermark PDF
- Choose your PDF by dropping it on the box or clicking to browse.
- Pick Text or Image. Type the watermark text, or choose a PNG or JPG logo.
- Adjust the look: font, size, color, opacity and rotation. The preview updates instantly.
- Choose the position (center, diagonal, tiled, top or bottom), the layer and the pages to watermark.
- Press Watermark & download PDF to save the file as name-watermarked.pdf.
Recommended watermark settings
| Use case | Text or image | Position | Opacity |
|---|---|---|---|
| Confidential report | CONFIDENTIAL, red or gray, bold | Diagonal | 15–25% |
| Work in progress | DRAFT, gray | Diagonal or center at 45° | 20–30% |
| Sharing scanned ID or documents | "Copy for [purpose], [date]" | Tiled | 25–35% |
| Photo or design proofs | Name or logo | Tiled | 20–40% |
| Branded handout | PNG logo | Top or bottom | 60–100% |
Watermarking documents you share
When you send a copy of an ID card, a passport or a bank statement to a landlord, employer or agency, a tiled watermark stating who the copy is for and the date makes it much harder to reuse the document for something else. Place the text so it crosses the photo and the key numbers while leaving them readable, and keep the original unwatermarked file safe.
- Be specific: "For ACME Lettings rental application only, 19 Oct 2026" is more protective than "COPY".
- Tile it: a single centered word can be cropped out. A repeated pattern cannot.
- Use over the content for scans, because a scan is one large image that would hide a behind-content watermark.
How the watermark is stored in the PDF
Text watermarks are written as real vector text in a standard PDF font, so they stay sharp at any zoom and add only a few kilobytes. Transparency uses the PDF graphics state opacity setting, which every modern viewer and printer supports. A logo is embedded once and reused on every page, so even a long document stays small. Rotation is calculated per page, which means the watermark looks the same on portrait, landscape and rotated pages.
Because the watermark becomes part of the page content, search and text selection in viewers may include the watermark text. That is normal for stamped watermarks.
Choosing a color and opacity that work
Opacity in a PDF works like tracing paper: at 25 percent, a black watermark looks like a light gray, and the text underneath remains readable. Strong colors such as red or blue read clearly at 15 to 25 percent, while pale colors such as yellow need 50 percent or more to be visible at all. If the document will be printed in black and white, test with a mid gray, because colors turn into similar grays on a monochrome printer.
- Large, bold fonts survive low opacity better than thin ones.
- Diagonal text crosses more lines of content, which makes it harder to crop or edit out.
- Short words such as DRAFT or COPY can be set larger than long phrases on the same page.
Frequently asked questions
How do I add a diagonal CONFIDENTIAL watermark to a PDF?
Open the PDF, keep the Text tab, type CONFIDENTIAL and choose Diagonal as the position. The text is rotated along the line from the bottom-left to the top-right corner and sized to fit each page automatically. An opacity of 15 to 30 percent keeps the document readable.
What opacity should a watermark have?
For text watermarks over documents, 15 to 30 percent is usually enough to be obvious without making the content hard to read. Logos placed in a corner can use 40 to 80 percent. Light colors need a higher opacity than dark ones.
What is the difference between over and behind the content?
Over the content draws the watermark on top, so it is always visible, but it sits over the text. Behind the content draws it underneath like paper printing. That looks cleaner on text documents, but it is hidden on scanned pages and on pages that have a solid white background, so check the result.
Can I add my logo as a watermark?
Yes. Switch to Image / logo and choose a PNG or JPG file. Transparent PNGs look best. Use the width slider to size the logo relative to the page, then choose center, tiled, top or bottom.
Can the watermark be removed?
A watermark added with this tool is real page content, so it shows in every viewer and when printing. Someone with PDF editing software could still delete it, so a watermark deters copying but is not a security control. Flattening by printing to PDF makes removal harder.
Why were some characters removed from my text?
The tool uses the standard PDF fonts, which only include Western Latin characters. Letters from other scripts and emoji are dropped. Use an image watermark if you need other characters.
Is my PDF uploaded to a server?
No. The PDF and the logo are processed entirely in your browser with the pdf-lib library and never leave your device.