Stamp a diagonal text watermark like CONFIDENTIAL or DRAFT across every page of a PDF.
The text runs diagonally at 45 degrees across the middle of every page, in bold light grey at 35% opacity, so the page underneath stays easy to read. Short words are set large (up to 60 points) and longer phrases are shrunk automatically so they fit on the page. The original PDF isn't changed, and the rest of each page isn't re-compressed.
The watermark uses a built-in PDF font that covers Latin letters, numbers and common punctuation. Emoji and non-Latin scripts such as Hindi, Arabic or Chinese can't be used; the tool will tell you if your text includes them.
The watermark is added as a separate layer of text on each page. That's normal for watermarks and keeps the file sharp, but someone with a full PDF editor could remove it. It's a clear label, not copy protection.
Not with this tool; it adds text only. For images, our Watermark Adder in the image tools can put a text watermark on a picture.
No, those are fixed: diagonal, centred, light grey and see-through. That combination stays readable on almost any page.
Yes. The watermark is drawn on top of whatever is on the page, including scanned images.
No. The watermark is added in your browser with pdf-lib.
OneClickly is a set of 119 free tools for PDFs, images, text, everyday math and code. They run in your browser, so the files and text you work with stay on your device.