Add Watermark

Purpose

Add text or image watermarks to a PDF, with full control over font, size, color, opacity, rotation, position, and tile-fill (page-wide pattern). Chinese characters render perfectly without uploading fonts. Runs locally via pdf-lib; no upload, no page limit, no product watermark (unlike many free online tools that brand your output with their logo). Use it to stamp contracts with "Draft", mark design samples with copyright, or label internal documents "Confidential" to deter leaks.

Steps

1. Drag or pick a PDF
2. Pick watermark type: "Text" or "Image"
3. For text, type the content (e.g., "Confidential", "DRAFT")
4. Tune font (default system fonts), size, color, opacity (20%-80% typical)
5. Set rotation (45° diagonal is most common) and position (center / corner)
6. (Optional) Enable "Tile entire page" so the watermark covers everywhere — harder to crop out
7. For image, drag a PNG (transparent background recommended) and adjust position/size/opacity
8. Pick scope: "All pages", "First page only", "Odd/Even pages", or custom range
9. The right-side preview updates live for the first page
10. Confirm and click "Process"
11. Download with "-watermarked" suffix

FAQ

Will my file be uploaded?

No. Watermarks are written into the new PDF via pdf-lib in your browser; the file never leaves your device. Especially important for sensitive internal documents — you don't want to leak the original to a watermark service.

Can the watermark be removed?

The watermark is written as real content (not as a separable annotation layer), so it can't be trivially stripped by a PDF editor. For maximum resistance to removal, enable tile-fill so the pattern covers the entire content area.

Does the tool itself stamp a product logo?

No. pdfbox doesn't add any product branding to your output — unlike free tiers of some services (SmallPDF free, for instance, brands the output). What you set is what you get.

Will Chinese watermarks render correctly?

Yes. pdf-lib uses your browser's system fonts (default Helvetica + sans-serif Chinese), so Chinese/English/numbers/symbols all render cleanly.

Can I watermark just the first page?

Yes. Pick "First page only" under scope — handy for cover-page stamps without polluting the body.

Use cases

• Mark contract samples with "Draft" or "For Reference" to prevent misuse
• Stamp copyright signatures on design PDFs to deter theft
• Label internal reports "Confidential" to deter external sharing
• Add preprint marks to academic papers before arXiv release
• Stamp date/version on financial reports for version control

Tip

For anti-removal robustness: 45° diagonal + tile-fill + semi-transparent (30-50%) is the gold standard. If you'll add a signature image on top, watermark first then run the Signature tool to overlay the signature.