Add Watermark to PDF Files Online
Sometimes you need to stamp a PDF as "CONFIDENTIAL" before sharing it, mark a draft document so no one treats it as final, or brand your proposals with your company name. This tool adds a custom text watermark diagonally across every page of your PDF. Type your text, adjust the size and transparency, and it's done.
You control how prominent the watermark looks. The opacity slider goes from barely visible (10%) to clearly stamped (50%), and you can pick from three font sizes. The watermark is permanently embedded — it's not a layer that can be easily stripped off.
Common Watermark Text
The most popular options people use are "CONFIDENTIAL" for sensitive business documents, "DRAFT" for documents still being reviewed, "SAMPLE" for demo or preview copies, and company names for branding outgoing proposals and presentations. But you can type literally anything — there are no restrictions.
Privacy and Processing
The watermarking runs in your browser using pdf-lib. Your PDF never gets uploaded to a server, so there's no risk to confidential content. Ironically, the tool you'd use to stamp something as "CONFIDENTIAL" is also private by design.
Frequently Asked Questions
Can the watermark be removed afterward?
No — the watermark is permanently embedded into the PDF content. Once it's applied and you save the file, it can't be stripped out. Always keep a copy of your original unwatermarked file.
Can I use a logo instead of text?
Not yet — the tool currently supports text-only watermarks. Image and logo watermark support is planned for a future update. For now, you can type your company name as text.
Will the watermark make the text hard to read?
At the default 20% opacity, the watermark is visible but doesn't obscure the page content. Drop it to 10% for an even subtler look, or push it to 50% if you want it really obvious. Experiment with the slider to find what looks right.
Where does the watermark appear on each page?
The text is placed diagonally across the center of each page at a 45-degree angle. It covers the middle of the page without blocking the corners or edges.
Is there a cost to use this?
No — it's completely free. No sign-up, no daily limits, and the tool doesn't add its own branding or watermark to your document.