PDF Watermark — Free Online Tool
Stamp a diagonal text watermark across every page of your PDF.
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Click to select a PDF to watermark
About PDF Watermark
The PDF Watermark tool stamps a diagonal text watermark across every page of your document, with control over the text, font size, and opacity. It is great for marking files as Confidential, Draft, or with your own branding.
The watermark is applied locally with pdf-lib and your file is never uploaded, so sensitive documents stay private. The watermarked PDF is generated instantly and ready to download for free.
How to Use PDF Watermark
- Click the upload area and select the PDF you want to watermark.
- Type your watermark text and adjust the font size and opacity.
- Click 'Add Watermark & Download' to stamp every page.
- The watermarked PDF downloads automatically to your device.
Key Features
Add custom diagonal text to every page
Adjustable font size and opacity slider
Semi-transparent stamp keeps content readable
100% client-side processing - files never leave your device
No signup, no page limits, and no forced branding
Frequently Asked Questions
Where is the watermark placed on each page?
The text is drawn diagonally across the center of every page at a 45-degree angle, so it overlays the whole document evenly.
Can I change how visible the watermark is?
Yes. The opacity slider lets you make the watermark faint or bold, and you can set any font size to match your page dimensions.
Are my files uploaded anywhere?
No. The watermark is added entirely in your browser using pdf-lib, so your PDF never leaves your device.
What text can I use for the watermark?
You can enter any text you like, such as CONFIDENTIAL, DRAFT, or a company name. The default is CONFIDENTIAL but it's fully editable.