Add Watermark to PDF
Stamp text across every page of a PDF — diagonal, adjustable opacity — all in your browser.
Ad space — replace with your AdSense unit
🔒 Your files never leave your device. Works with files up to 100MB.
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Drop a PDF here or click to choose
How it works
Using the open-source pdf-lib library, this tool draws your text diagonally across every page of the PDF at the opacity you choose, then saves a new file. The original is never uploaded — processing happens entirely in your browser, so it's safe for sensitive documents you need to mark as draft, confidential or copyrighted.
Frequently asked questions
Is my PDF uploaded?
No — the watermark is applied in your browser with pdf-lib; the file never leaves your device.
Can I change the opacity?
Yes — adjust opacity and font size before applying. The text is drawn diagonally on every page.
Will it work on scanned PDFs?
Yes, it stamps text over any PDF pages, including scans.