💧 Add Watermark to PDF
Add a text watermark across your PDF pages, set the wording, size, opacity and angle, then download. The file is processed on your device.
How the add watermark to pdf works
The tool loads the PDF with pdf-lib, embeds a standard Helvetica Bold font, and draws your text onto each selected page at the opacity and size you choose. Opacity is a value from 0 (invisible) to 1 (fully solid), so a setting of 0.15 lets the underlying text show clearly through the stamp. With the diagonal option the text is rotated 45° and centred by stepping back along its own baseline, half the rendered text width in the direction of the rotation, so it sits squarely in the middle of the page whatever its length. Pages are edited in place, the rest of the document is untouched, and the whole operation happens in your browser, so the file is never uploaded.
A watermark drawn this way becomes part of the page content, so it will not simply toggle off in a viewer. It is not a security measure, though: anyone determined can edit the PDF or cover the text. Use it to mark status, DRAFT, SAMPLE, INTERNAL, rather than to protect a document. If you need genuine restriction, add a password with the PDF protect tool instead. Keep opacity low (10-20%) so the underlying text stays readable.
Frequently asked questions
How do I add a watermark to a PDF?
Choose your PDF, type the watermark text, set size and opacity, and download. By default the text is drawn diagonally across the centre of every page. Everything happens in your browser, the file is never uploaded.
Can I watermark only certain pages?
Yes. Leave the page field empty to watermark every page, or enter a range like 1-5 or 2, 4, 7 to mark only those pages.
Is the watermark removable?
It is drawn into the page content rather than added as a separate toggleable layer, so it will not switch off in a normal viewer. It is not tamper-proof, though, a determined person with PDF editing tools can remove or obscure it.
Does a watermark protect my document?
No. It marks status and discourages casual misuse, but it does not restrict opening, copying or printing. For actual restriction, use password protection instead.
What opacity should I use?
Around 10-20% usually reads clearly as a watermark while leaving the document text legible underneath. Higher values start to compete with the content.
Is my PDF uploaded?
No. It is parsed and rewritten by pdf-lib inside your browser, so the document never leaves your device and the tool works offline once loaded.
Can I add an image or logo as the watermark?
This tool stamps text, words like DRAFT, CONFIDENTIAL or a name, rather than an image. Text watermarks stay crisp at any zoom and keep the file small, and they cover the most common status-marking needs.
Why is a diagonal watermark centred no matter how long the text is?
The tool measures the rendered width of your text in the chosen font and size, then offsets the starting point by half that width along the 45° angle. That way short words like "PAID" and long ones like "CONFIDENTIAL, DO NOT COPY" both end up centred on the page.