Add watermark
Stamp text across every page. Drop as many PDFs as you like.
Runs on your device. The file is never uploaded.
Add watermark draws one line across every PDF page, centred, reading DRAFT unless you change it. Size 48, opacity 0.2 and a 45 degree turn are the defaults you can change; Helvetica Bold and mid grey are fixed. Nothing shrinks the line to fit, so a long string runs off the page edges.
Questions
Is a watermark from this tool secure?
No, and do not treat it as one. The text is drawn on top of the page content as ordinary PDF graphics, so anyone who can open the file in an editor can select it and delete it. It marks a document as a draft or a copy; it does not protect it. For real restrictions use Protect PDF.
What can I change about the look?
Four things: the text, which defaults to DRAFT, the font size, which defaults to 48, the opacity, which defaults to 0.2, and the rotation angle in degrees, which defaults to 45. Colour is fixed at mid grey and the typeface is fixed at Helvetica Bold. The stamp is a single line, centred on each page.
Why was my opacity or angle rejected?
Opacity has to sit between 0 and 1 inclusive, and anything else gets "opacity must be between 0 and 1". Percentages like 20 are the usual mistake; type 0.2. The angle must be a number, but any number is fine, including negative ones and values over 360. Font size must be greater than zero.
Does the watermark go on every page?
Yes, all of them. There is no page range setting, so you cannot watermark a cover only or skip the last page. The text lands in the same place on each page, centred and rotated, with its position worked out from the page size so it stays centred on mixed page sizes.
Can I watermark several PDFs at once?
Yes. Drop as many as you like and each comes back separately with a -watermarked suffix. The same text, size, opacity and angle are applied to each one. Nothing is uploaded: pdf-lib does the drawing in a Web Worker in this tab.
Can I use an image or a logo as the watermark?
Not here, this tool draws text only. Sign PDF takes a PNG or JPG and stamps it onto one page, which covers a logo in a corner. There is no tool that tiles an image across every page, so an image watermark on a whole document is not something this site does.