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Add Watermark to PDF

Stamp a text watermark across every page of a PDF locally and download the result.

Runs in your browser — files never leave your device

How it works

Type a word or two — DRAFT, CONFIDENTIAL, a client name — and the tool stamps it diagonally across every page of the PDF using the open-source pdf-lib library, entirely in your browser. The result downloads as watermarked- plus the original filename.

The stamp’s look is deliberately fixed: bold Helvetica at a 45° angle, through the center of the page, in a soft indigo at 18% opacity — dark enough to read, light enough that the text underneath stays comfortably legible. The size scales with each page (an eighth of the shorter page dimension), so A4 pages, US Letter pages, and landscape spreads in the same file each get a proportionate mark. Every page is stamped; there’s no page selection.

The text is drawn into each page’s content, on top of the existing artwork. That means it becomes part of the page itself — not a floating annotation a reader can click and delete, and not a view-only overlay that disappears in print. It prints, exports, and screenshots with the document.

Two honest limits. A watermark is labeling, not protection: PDF editing software in determined hands can strip content from a page, so treat the stamp as a clear statement of status or ownership, and pair it with the add-password tool when you need actual access control. And the text is set in a standard Latin font — stick to ordinary letters, digits, and punctuation, since emoji and most non-Latin scripts can’t be encoded and will produce an error. Short strings work best; the stamp is sized for a word or two, and very long text can run past the page edges.

Documents that need watermarks — agreement drafts, pre-release reports, portfolio samples — are usually the sensitive ones, so it’s worth saying plainly: the file is stamped in your browser’s memory and downloaded from your device. It is never uploaded, queued, or stored anywhere.

Frequently asked questions

Where does the watermark appear, and can I style it?
It’s stamped diagonally at 45° through the middle of each page in bold type, in a light indigo at 18% opacity. The styling is intentionally fixed at values that stay readable without obscuring content; the text is the part you control. Size adapts to each page, so mixed page sizes all get proportionate stamps.
Does it go on every page?
Yes — all pages get the stamp in one pass; there’s no page-range option. If only some pages should be marked, split the file first, watermark the part that needs it, and merge the pieces back together.
Can the watermark be removed?
Not casually — the text is merged into the page content, not added as a deletable annotation. But someone determined, with PDF editing software, can strip content from a page, so a watermark labels a document rather than protects it. For actual protection, add a password too.
What text can I use?
Short Latin text works best — letters, digits, and common punctuation in the standard Helvetica Bold font. Characters outside that set, such as emoji or most non-Latin scripts, can’t be encoded and produce an error. Keep it to a word or two: the stamp is sized for that, and very long strings can overflow the page edges.
Does watermarking change the original content or quality?
No — existing text, images, and layout are untouched; the stamp is added as vector text on top. The document stays selectable and searchable, and note that the watermark itself is real text too, so it will show up in text searches of the file.
Is the PDF uploaded to watermark it?
No. The file is loaded into your browser’s memory, the text is drawn onto each page locally, and the stamped copy downloads from your device. Nothing is transmitted — appropriate, given that watermarked documents are usually the confidential ones.

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