PDF Watermark

What the PDF Watermark does

The tool overlays a text watermark on a PDF. Your word or phrase goes large and diagonal across the middle of each page, faint enough that the content underneath stays readable and clear enough to show the document's status.

Use it to label a PDF as a draft, confidential, a sample or a copy, so anyone who sees or prints it knows how to treat it.

How it works

The tool opens the PDF, embeds a bold standard font and draws your text across the centre of each page at 45 degrees, in grey at about thirty percent opacity. The underlying content shows through and the watermark stays visible.

The text is drawn into the page content, so it becomes part of each page. All pages are stamped in one pass and the new file is saved for download. The watermark marks the document but doesn't encrypt or lock it.

Processing pipeline

1. Open the PDF. Load the document and embed a bold font.
2. Take your text. Use the watermark text you enter, such as CONFIDENTIAL.
3. Stamp each page. Draw the text diagonally across the centre of every page, semi-transparent.
4. Save the file. Save and download the watermarked PDF.

What it stamps

The watermark is drawn onto the page, so it is visible and it prints. Someone who re-processes the PDF can still remove it, so treat it as a deterrent and not as document security.

Privacy

The PDF stays on your device. Your browser reads it, draws the watermark and builds the new file locally, and keeps no copy anywhere.

There is no account and the tool saves nothing. Refresh or close the tab and the original and the watermarked file are both cleared from memory.

Standards and references

• Visible overlay: The watermark is low-opacity text drawn onto the page, so it shows over the content and appears in print. Anyone viewing the document sees its status.
• A deterrent, not security: The watermark is drawn onto the page, and the PDF isn't encrypted, so re-processing the file can remove it. It discourages casual misuse but doesn't protect or lock the document.
• Applied to every page: All pages are stamped in one pass with the text diagonally across the centre, so the whole document is marked the same way, not just the first page.

Accuracy and limits

The mark looks the same on every page: your text runs diagonally across the page, faint enough to read through and plain enough to work as a label.

The watermark isn't tamper-proof. It is part of the page content, and someone who re-processes the PDF can remove it. It puts off casual copying, but real protection needs encryption or rights management.

Position and size are fixed and the text is centred with a simple estimate. Very long text may run past the page edges and very short text sits small in the middle.

Only text is supported. You can't use an image or logo, tile the mark across the page or vary the text by page. Every page gets the same word or phrase in the same style.

Real-world uses

When it fits, and when it doesn't

For real protection, use PDF encryption or rights management, which restrict access to the file. A full PDF editor can add a logo or a tiled watermark. This tool adds a visible text watermark.

Frequently asked questions

References

• PDF 2.0, ISO 32000-2 (Library of Congress format description)
• pdf-lib: PDF library
• Digital watermarking (Wikipedia)
• Portable Document Format (Wikipedia)

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