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Free tools · PDF

Watermark PDF

Your words, diagonally, at the opacity you choose.

Free · no sign-up · no watermark · up to 50 MB · uploads deleted after 24 hours, results after 7 days.

How to watermark pdf

  1. Drop the PDF.
  2. Type the watermark text and pick an opacity.
  3. Press Watermark and download.

What happens to your file

The text is drawn diagonally across each page in grey at the opacity you chose, over the existing content. Text underneath stays selectable.

A watermark is a mark, not a lock: it discourages reuse and identifies copies, but a determined editor can remove it. Use Protect PDF for access control.

Questions

Can I use an image as the watermark?

Not on this page — text only. The API supports both.

Does it cover the text underneath?

At the recommended opacity the page stays fully readable; at 50% it is deliberately intrusive.

Do this in code

curl -X POST https://api.fylane.dev/v1/jobs \
  -H "Authorization: Bearer $FYLANE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "file_id": "<file id>",
    "operation": "pdf.watermark",
    "options": {
      "text": "CONFIDENTIAL",
      "opacity": 0.3
    }
  }'

The same operation, pdf.watermark — Grey diagonal text across every page, opacity yours. Upload first with the quickstart; every option is on the operations page. 500 free credits a month, then $5 per thousand.