How to add a watermark to a PDF
- Drop a PDF into the box above (one file, max 100 MB).
- Type the watermark text — typically CONFIDENTIAL, DRAFT, your name, or a date.
- Tweak color, opacity, rotation, and font size. Lower opacity (0.2–0.4) keeps the original content readable.
- Click Add watermark. The marked file downloads instantly.
Designing a good watermark
A diagonal watermark at −45° with around 30% opacity and 60–80 pt Helvetica is the conventional "DRAFT" look. For a more subtle stamp, drop the opacity to 0.15. Avoid pure black on dark scans — gray (#888888) usually reads better.
Privacy
The watermark is drawn into a copy of your PDF using pdf-lib in the browser. The original file is left untouched on disk and nothing is uploaded.
FAQ
Can I add an image watermark instead of text? Not yet — this tool currently supports text only. For an image watermark, use Images to PDF with a transparent PNG overlay tool offline.
What characters are supported? Standard ASCII renders cleanly via the built-in Helvetica font. Non-Latin scripts (Korean, Chinese, Arabic, etc.) require a custom font and aren't supported in this version.
Will the watermark protect my document legally? No. A watermark is a visual deterrent, not encryption. For real protection, encrypt the PDF in a desktop tool.