Add Watermark

Stamp custom text diagonally across every page of your PDF. Choose the colour and opacity to make the brand mark as subtle or bold as you need.

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Add Watermark to PDF — Stamp Text Across Every Page, Locally

The Watermark tool at PDFGuru lets you stamp custom text diagonally across every page of a PDF. Watermarks are commonly used to mark documents as "CONFIDENTIAL", "DRAFT", "COPY", "INTERNAL", or as a gentle brand reminder such as a company name. They discourage redistribution by making it obvious the file belongs to a specific owner.

You can type any text up to sixty characters. Choose any colour via the colour picker or by typing a hex code directly. The opacity slider runs from 10% (barely visible brand reminder) to 100% (full-visibility stamp). A separate font-size slider controls the size. The text is automatically rotated 45 degrees so the stamp reads diagonally across the centre of each page.

We use pdf-lib to draw directly onto the page content stream of every page in your PDF. The original text content and font layers are preserved — only the watermark text is added on top. Output runs entirely in your browser; no document ever leaves your machine.

For professionals sharing contracts under limited distribution, legal teams pre-stamping research findings as "CLIENT PRIVILEGED", educational institutions branding downloadable workbooks, businesses issuing internal training materials marked "DO NOT REDISTRIBUTE", or developers publishing draft API specifications as "BETA" — this tool is your one-click local alternative to expensive desktop PDF editors.

Try the watermark tool above with any PDF — there is no signup, no quota and absolutely no upload. You can stamp dozens of pages in seconds with zero server round-trips.

Watermark PDF — Frequently Asked Questions

The current build only stamps text. For image watermarks we recommend merging the watermark image with each page's first photo layer using our Photos to PDF tool with reordered files.
The 14 standard PDF fonts defined by the PDF spec are available — Helvetica, Times Roman and Courier in regular and bold. We default to Helvetica Bold which renders nicely as a diagonal watermark.
Only marginally — a few hundred bytes per page added to the content stream. There is no perceptible change for typical documents.
Currently watermarks stamp every page. To watermark a subset, split the document first using Split PDF, watermark only the range you need, then merge the result back with Merge PDF.