Stamp CONFIDENTIAL, DRAFT, SAMPLE, or any text across every page of a PDF — centered and diagonal like a rubber stamp, or tiled edge-to-edge so it cannot be cropped out. You see the watermark on the live page previews before you commit, and the file never leaves your browser.
How to add a watermark to a PDF
- Drop your PDF in the box — every page renders as a preview thumbnail.
- Type the watermark text and tune it: size, opacity, color, diagonal, single or tiled.
- Watch the preview update live, then click Add watermark and download the result.
Single or tiled?
The single centered watermark is the classic: one large diagonal word behind the content. It reads instantly (“this is a draft”) and barely interferes with the text. The tiled layout repeats the text in a staggered grid across the entire page — the standard treatment for confidential material, because there is no clean corner left to screenshot or crop. Pair tiling with a smaller font size (24–32 pt) so the repetition stays subtle.
Getting the look right
Opacity is the setting that makes or breaks a watermark. Too strong and the document becomes hard to read; too faint and nobody notices it. Start at 20%: visible in print and on screen, harmless to readability. Gray is the professional default; red signals urgency (UNPAID, VOID); blue works when gray disappears into grayscale scans. The diagonal 45° angle isn’t just tradition — slanted text is harder for automated tools to detect and erase cleanly than horizontal text.
What this tool does and doesn’t do
It stamps live text into the page content stream using the PDF’s built-in fonts, so the output stays small, crisp at every zoom level, and prints exactly as previewed. It supports Latin letters, numbers, and punctuation (the standard PDF fonts don’t cover other scripts). It marks every page the same way — if you only need certain pages marked, split the PDF first, watermark the part that needs it, and merge the pieces back. To stamp page numbers instead of a watermark, use the page numbers tool.
Private by design
Watermarking is usually applied to exactly the documents you would not want on someone else’s server: contracts, financials, unpublished work. Here the entire operation — reading, stamping, saving — runs in your browser. Nothing is uploaded, nothing is stored, and closing the tab leaves no trace.