PDF Watermark Adder

Stamp every page of a PDF with a diagonal text watermark (DRAFT, CONFIDENTIAL, …).

Add diagonal text watermarks to PDFs in your browser. Free PDF watermark tool with size, color, opacity and angle control.

PDF documents up to 50 MB. Files never leave your browser.
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About Watermark PDF

Stamp every page of a PDF with a diagonal text watermark (DRAFT, CONFIDENTIAL, …).

Enter the stamp text, size, color, and opacity. Every page gets the same centered diagonal mark sized relative to the page, so mixed-orientation documents stay consistent.

Watermarks deter casual misuse but determined editors can remove them — for legal weight, pair with access controls. Files stay in your browser; only the small writer library loads from CDN.

Where it is used

Marking drafts and previews, branding shared documents, deterring casual copying, and flagging review copies.

How to use the Watermark PDF

  1. Select PDF — select a file (application/pdf,.pdf) — PDF documents up to 50 MB. Files never leave your browser..
  2. Watermark Text — enter the value (e.g. CONFIDENTIAL).
  3. Font Size (% of page) — enter the value in % (e.g. 12).
  4. Color (hex) — enter the value (e.g. 888888).
  5. Opacity (%) — enter the value in % (e.g. 25).
  6. Calculate — press the Calculate button to see the result instantly above.

Formula

DrawText centered-diagonal per page at size% opacity, then save.

Examples

Example

watermarkText:DRAFT
fontPct:12
colorHex:888888
opacityPct:25
Result: Select a PDF → every page stamped DRAFT diagonally

Frequently Asked Questions

Will it cover the content?
At 25% opacity it tints without hiding. Raise opacity for stronger deterrence, lower it to preserve readability.
Can the watermark be removed?
Yes, with PDF editors — treat it as a signal, not security. Real protection means access control, not overlays.
Why diagonal and centered?
Maximum coverage with minimum text: one diagonal stamp crosses every region a crop could isolate.
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