How to watermark a PDF
- Select Choose file or drop your PDF on the box.
- Type the Watermark text, or select Use a logo image instead of text and pick an image.
- Choose the Layout: one in the center, or repeated across the page. Set Opacity, Rotation, size and color.
- Optionally list pages in Pages, like
1-3, 5. - Select Add watermark, then Download.
Text and image watermarks
A text watermark is drawn in bold Helvetica at the size you choose, tilted by the rotation angle (45 degrees is the classic diagonal) and made see-through with the opacity slider. An image watermark is sized as a fraction of the page and uses the same angle and opacity. A transparent PNG logo blends in best. Text in scripts such as Hindi, Arabic or Chinese is drawn with your device’s own fonts and then placed as an image, so it never turns into empty boxes.
Centered or tiled
One in the center puts a single mark in the middle of each page, which is right for DRAFT or CONFIDENTIAL stamps. Repeated across the page tiles the mark in a staggered pattern over the whole page, which makes it much harder to crop out and suits samples, proofs and previews.
Good uses
Marking contracts as draft, labelling copies for a named recipient, adding a company logo to reports, protecting a sample chapter or discouraging reuse of artwork.
Tips
- Keep opacity between 15 and 30 percent so text underneath stays readable.
- Number pages with Add page numbers to PDF, before or after watermarking.
- Combine documents first with Merge PDF.
- Rotated pages are handled: the mark stays upright for the reader. Fix sideways scans with Rotate PDF if needed.
- Keep a spare copy of the original file.
The work is done on your device with pdf-lib. Your file and logo are never uploaded.