Add Watermark to PDF β Diagonal Text Stamp Online
Stamp a diagonal text watermark across every page of a PDF with custom text, size, color and opacity, then download. Applied in your browser, never uploaded.
π Runs entirely in your browser. Your input and output are never sent to a server or stored β fully private.
π The watermark is applied in your browser β your PDF is never uploaded.
About this tool
This tool stamps a diagonal text watermark across every page of a PDF, in your browser. Type your text β such as "CONFIDENTIAL" or "DRAFT" β set the size, colour and opacity, and download the watermarked file. It is a fast way to mark drafts, label copies, or discourage casual reuse. Nothing is uploaded: the watermark is applied locally, so even confidential documents never leave your device.
Frequently asked questions
Can the watermark be removed by the recipient?
It is drawn into the page content, so it cannot be toggled off like a layer, but a determined person with editing software could still remove it. Treat it as a clear visual label β for marking drafts and copies β rather than as strong security or copy protection.
Can I change how strong it looks?
Yes. Adjust the opacity so the watermark is a faint background tint or a bold overlay, and set the font size and colour to suit. A light grey at low opacity stays readable over the text underneath, while a stronger setting makes the label unmistakable.
Does watermarking upload my PDF?
No. The text is drawn over each page by code in your browser, so the document is processed entirely on your device and never reaches a server. That is exactly why it is safe to stamp "CONFIDENTIAL" on a file that genuinely is confidential.