Add a watermark to a PDF online, free
« CONFIDENTIAL » on a draft contract, « COPY » on a duplicate, the recipient's name on every copy you send: pick the text, the pages and the strength. Certyneo Reader works inside your browser, the document goes nowhere.
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The same PDF reader, installed on your computer: it opens your files offline, with no account, and can become your default PDF reader.
Does Windows show “Windows protected your PC”? That is the usual warning for a newly released app: click “More info”, check that the publisher is Certyneo, then click “Run anyway”.
Other systems and installers: macOS · Linux (AppImage) · Linux (.deb package for Debian and Ubuntu)
Windows (offline installer, MSI for managed fleets)
Windows (offline installer, x64) · Windows (offline installer, ARM64) · Windows (MSI for managed fleets)
Drop your PDF here
or choose a file on your computer, tablet or phone
Word, Excel, PowerPoint, text, RTF, images and HEIC photos are converted to PDF on your device.
100% local reading: the document is never sent over the internet.
Add a watermark in three steps
- 1
Open the document
Drag the PDF into the reader or pick it from your device, then open the « Watermark » tool.
- 2
Write the text
Type your wording, or take « CONFIDENTIAL », « COPY » or « DRAFT » in one click. Set the strength so it reads without getting in the way.
- 3
Every page, or some
Apply to the whole document or enter specific pages (1-3, 7), then save.
Everything happens in your browser: the file never leaves your device. Open in the reader
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Frequently asked questions about watermarks
Does a watermark protect my document?
No, and that matters: a watermark can be removed. It signals an intent — « do not circulate », « copy for Ms Martin » — and discourages resharing, but it hides nothing. To really remove information, use redaction, which deletes the text instead of covering it.
Is my PDF uploaded to a server?
No. The watermark is drawn inside your browser. Certyneo never receives, stores or reads your document, and adds no promotional mention.
Does the watermark go behind the page content?
It is drawn on top, deliberately. Slipped underneath, it would vanish behind the white background most word-processor PDFs paint on their pages.
Can I write in Cyrillic, Greek or Japanese?
Not yet: a PDF's standard fonts only write the Latin alphabet and its accents. Text they cannot write is refused before saving, rather than produced as gibberish for the recipient.
Can I remove an existing watermark?
Not with this tool. A watermark is part of the page content: removing it cleanly means rebuilding the page. Always keep your original, watermark-free document.
Does this PDF need to be signed?
Send it for electronic signature in minutes: your signers sign from their phone, without creating an account.
Get started with Certyneo for free