About watermark PDF
A watermark is drawn text, added to a page's content stream after everything already there. Mechanically it is the same kind of object as the body text: a string, a font reference, a position, a graphics state carrying the transparency value. Because it is appended last it renders on top, and because it is a real text object rather than a flattened image the underlying content stays selectable and searchable — the watermark itself is selectable too, which is worth knowing. This tool exposes the parameters that actually decide whether the result looks deliberate: placement, opacity, point size, rotation angle and colour. Opacity is the parameter people get wrong most often. Below about 15% a watermark disappears when printed on a monochrome printer; above 40% it competes with the text it sits over and makes the document harder to read than it needs to be. Everything is applied in your browser, so a document marked confidential is not uploaded to somebody else in order to be labelled confidential.
How to watermark PDF
- 01
Load the PDF
Choose the document that needs marking. Page dimensions are read so placement adapts to each page size.
- 02
Write the text
Keep it short. A word or a short phrase in capitals reads far better at an angle than a sentence.
- 03
Tune placement and opacity
Pick a placement, then set opacity so the mark is unmistakable but the content underneath stays comfortable to read.
- 04
Apply and download
Press Add Watermark and save the marked copy. Keep your unmarked original — the mark is not cleanly reversible.
What this tool does
- Five placements including tiled, which is the hardest to crop out
- Independent control of opacity, point size, rotation and colour
- Page-range targeting, so a mark can apply to part of a document
- Placement adapts per page, so mixed page sizes and orientations stay correct
- Runs locally — a confidential document is never uploaded to be labelled
Limitations worth knowing
Every PDF tool has constraints. Stating them plainly is more useful than discovering them halfway through your work.
- A watermark is not a security control. It sits on top of the content and anyone with a PDF editor can remove it. It labels and deters; it does not protect.
- Text uses an embedded standard font, so non-Latin scripts such as Chinese, Arabic or Cyrillic may not render.
- The watermark is real text, which means it can be selected and copied along with the page content.
- On dense pages some overlap with existing content is unavoidable — that is the nature of drawing over a finished layout.
How your file is handled
This tool runs entirely inside this browser tab. When you choose a file, your browser reads it from your own disk and hands the bytes to JavaScript running on this page — no network request carries your document anywhere. You can confirm that yourself: open your browser’s developer tools, switch to the Network panel, and run the tool. You will see no upload.
Nothing is stored after the fact. Closing or reloading this tab discards the file, the result and everything derived from them, because none of it ever left your machine. Read how local processing works.
Questions about watermark PDF
Can a watermark be removed from a PDF?
Yes, by anyone reasonably determined. It is an object in the content stream, and editing tools can delete it. Treat a watermark as a label and a deterrent, never as protection. If you need the content restricted, encrypt the file.
What opacity should I use?
20–30% for most documents. Lower and it may vanish on a monochrome printer or a low-contrast screen; higher and it starts interfering with reading the text it covers.
Why does my watermark text show as blank boxes or nothing at all?
Because the mark is drawn with an embedded standard font whose character set is Latin. Anything outside it — Chinese, Japanese, Arabic, Cyrillic, Greek — has no matching glyph, so there is nothing for the renderer to place.
Does watermarking degrade the document?
No. Existing page objects are untouched and nothing is re-rendered or re-compressed. Text stays selectable, images keep their original data, and only a small text object is added per page.
Can I put a logo image on instead of text?
Not with this tool — it draws text. For an image overlay, add the image with an editing tool, then flatten if you want it merged into the page content.
Tools that pair with this one
- Text Watermark PDFA text watermark, with the font realities spelled out up front.
- DRAFT Stamp PDFMake sure nobody mistakes an unfinished document for the final one.
- CONFIDENTIAL Stamp PDFClassify a document’s handling on the page — then encrypt it properly.
- Watermark All PagesEvery page marked, whatever its size or orientation.
- Batch Watermark PDFStamp the same mark across every page of every file in one pass.
- Add Page NumbersStamp numbers onto your pages, positioned exactly where you want them.
Read more about this
- How to sign a PDFThis site does not add electronic or cryptographic signatures. Use this guide to distinguish a visible mark from a certificate-backed signature and choose an appropriate external workflow.5 min guide
- How to add a watermark to a PDFWatermarking writes text into the page content. This guide covers the settings that make it legible without obscuring the document, and what it does not do.5 min guide