PDF Watermark & Page Numbers

Stamp a text watermark or page numbers on any PDF — pick font size, opacity, rotation, colour and placement, compare the output size, and download.

All processing happens locally in your browser. Your PDF never leaves your device.

Watermark Options

Drop a PDF here or click to browse — one PDF at a time

Mode
Placement

Opacity is baked in by blending the chosen colour toward white, which assumes white page backgrounds — light colours on white pages can be nearly invisible.

How PDF Watermarking Works

Everything here is done with the open-source pdf-lib library running entirely in your browser. There is no upload step — the file never leaves your device.

Draw Order — The Watermark Sits on Top
A PDF paints its content stream in order, so text appended after loading a page is drawn over the existing content. That makes the watermark clearly visible on screen and in print (it survives printing because the output is a static PDF — nothing re-renders at print time), but it is a visual mark, not a security feature.
Opacity by Colour Blending
pdf-lib has no alpha channel for text, so the chosen opacity is baked in by mixing your colour toward white: channel = colour × opacity + 255 × (1 − opacity). A grey #999999 at 15% becomes a very light grey that looks exactly like a translucent stamp on white paper. On dark page backgrounds the blend assumption breaks — the mark shows brighter than intended.
Page Numbers with {n} and {N}
In Page numbers mode the format string is templated per page: {n} is replaced with the current page number plus your start offset, and {N} with the document's total page count — giving 'Page 3 of 12' style footers for court filings and exam papers.
Standard Font Encoding
The tool uses the built-in Helvetica standard font, which only covers the WinAnsi (Latin-1 style) character set. Non-Latin scripts like Chinese, Arabic or Cyrillic cannot be rendered by this font — the tool detects them and warns you to use ASCII text rather than producing garbled output.

Frequently Asked Questions

Does a watermark protect my document?

A watermark deters casual misuse and signals that a document is confidential or a draft — it does not prevent anything. The mark is drawn as ordinary text painted on top of each page, so a determined reader can still use the content. For real protection, encrypt the PDF with a password and control access; this tool deliberately doesn't touch copy protection.

Can someone remove the watermark later?

Yes, with effort. The output is a normal PDF where the watermark lives as its own text objects, so a PDF editor can select and delete them, and re-printing to PDF also strips them. What is true: the download is a static, flattened-looking file — the watermark is baked into the page layout, so anyone printing or viewing it sees the mark; there is no toggle to hide it in a plain viewer.

Why does the opacity setting top out at 60%?

pdf-lib's text drawing has no alpha channel, so we simulate transparency by pre-mixing your colour with white: each channel becomes colour×opacity + 255×(1−opacity). That looks exactly like true transparency on white paper — but only on white. Very light colours or high opacity limits keep the blend predictable; a pale yellow at 10% would simply vanish, so the slider range keeps results visible.

Can I add court or exam style page numbers like 'Page 3 of 12'?

Yes — switch to Page numbers mode and use the {n}/{N} template (e.g. 'Page {n} of {N}', '{n} / {N}', or just '{n}'), pick bottom-center, bottom-right or top-right placement, and set a start offset when the first sheet is a cover page. Court filings, exam papers and exhibit bundles are exactly what this mode was built for.

Is anything uploaded to a server?

No. Your PDF is parsed, stamped and saved entirely in your browser with pdf-lib. There is no upload step, no account, and no network request that contains your file.

When Not To Use This Tool