Add a watermark to a PDF
Stamps text over the pages of a PDF. You can set the font size, opacity, angle and colour.
How to use it
- Drag your .pdf files onto the area above, or press "Choose files".
- If options are shown, set them as you like. They appear below the file list.
- Press "Convert". The conversion runs on your device, shows its progress and can be cancelled at any time.
- Press "Download" next to a result. With several results, "Download all as ZIP" gets them in one go.
- The first time, the page downloads the conversion program (about 0.2 MB). It is kept on your device, so later visits do not download it again. Your files are not sent during this step either.
The formats involved
PDF .pdf
PDF is a file format that keeps a document as a sequence of pages.
Typical uses: sending and archiving documents
Limits and things to watch for
- The file size that can be processed depends on your device. The limit for your device is shown in the drop area, and files above it are refused with a message.
- The pdf-lib library we use does not support password-protected PDFs (its README: "does not currently support encrypted documents"). This site does not offer to remove passwords either.
FAQ
Is my file uploaded to a server?
No. Conversion happens only inside this browser, and file names, contents and results are not sent to our servers. Some converters download their conversion program (code) the first time you use them; your files are not sent then either. See the privacy page for details.
Can I convert many files at once?
Yes. Select several files and they are processed one after another; save the results one by one or all at once as a ZIP. How much can be handled at once depends on your device memory and is shown on the page.
Can I merge password-protected PDFs?
No. The pdf-lib library we use does not support encrypted documents, and this site does not offer to remove passwords. If such a file is included, the conversion stops with a message.
Is the text this tool puts into a PDF a picture or real text?
It is drawn as real text, not as a picture. For Korean and Japanese, pieces of a font are embedded in the PDF, and Latin letters and numbers of a watermark are drawn in Helvetica-Bold.
Licences and the software used
Programs this converter downloads and uses: pdf-lib 1.17.1 (MIT) · Open-source licenses
Sources and check date
- pdf-lib (GitHub README)
Features: copy pages between PDFs; encrypted documents are not supported · 2026-11-10
Date we opened the original documents ourselves: 2026-11-10. Specifications can change, so read the original again before anything important.