Add a watermark to a PDF

Add a watermark to a PDF online, free and entirely in your browser. This PDF watermark tool stamps a diagonal text watermark across every page, so you can mark documents as CONFIDENTIAL, DRAFT, COPY, or anything you type. Adjust the font size and opacity to get a subtle background mark or a bold, eye-catching stamp. Because everything runs locally with no uploads, your PDF never leaves your device, making it safe for contracts, reports, and other sensitive files.

🔒 100% private — files never leave your device

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How to use

  1. Drag and drop your PDF file into the upload area, or click to browse and select it from your device.
  2. Type the watermark text you want, such as CONFIDENTIAL, DRAFT, or your company name.
  3. Set the font size and drag the opacity slider until the diagonal watermark looks right.
  4. Click Apply, then download your watermarked PDF with the text stamped on every page.

Frequently asked questions

What kind of watermark does this tool add?

It adds a text watermark, stamped diagonally at 45 degrees and centered on every page of the PDF. You choose the text, the font size, and the opacity for a subtle or bold look.

Can I add an image or logo as a watermark?

No. This tool watermarks PDFs with text only. You can type any phrase, such as CONFIDENTIAL or your company name, but it does not support image or logo watermarks.

Is my PDF uploaded to a server?

No. Everything happens 100% in your browser. Your PDF is processed locally on your device and is never uploaded, making it safe for confidential and sensitive documents.

Does the watermark appear on every page?

Yes. The watermark text is applied to every page of the PDF automatically, so multi-page documents are fully marked in one click.

Can I control how visible the watermark is?

Yes. Use the opacity slider to make the watermark faint and translucent or strong and prominent, and set the font size from 8 to 200 to control how large it appears.

Is there a file-size limit?

There is no fixed limit. Since the PDF is processed in your browser using your device's memory, very large files depend on your available RAM, but typical documents work without any problem.

About this tool

Add a diagonal text watermark such as “CONFIDENTIAL” or “DRAFT” to every page of a PDF, with adjustable size and opacity. Processed entirely in your browser.

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