Can the watermark be removed?
Yes, by anyone determined enough. It is a deterrent and a label, not a security control.
Watermark a PDF
Diagonal text across every page, drawn into the page content. Nothing uploaded.
Drop PDF files here
or · max 10 files free
What a watermark is actually for
A watermark is a deterrent, not protection. Anyone with the file can crop it out of a scan or re-export a page without it. What it does do is make a leaked copy traceable in conversation, and signal to a recipient that the document is a draft or a confidential review copy.
That makes placement matter more than strength. A grey diagonal stamp at low opacity reads as professional. A giant red block over the content makes the document unusable and gets ignored. This tool defaults to subtle diagonal grey at 28 percent opacity.
How this watermark behaves
The details that decide whether it looks intentional or cheap.
| Detail | Behaviour | What it means |
|---|---|---|
| Position | Centred, rotated 45 degrees | Diagonal across the middle. The conventional placement, and the hardest to ignore. |
| Opacity | 28 percent | Visible without obstructing. Enough to notice, not enough to make the page unreadable. |
| Colour | Mid grey | Grey survives printing on any printer and reads as a stamp rather than an error. |
| Font size | 9 percent of the shorter edge | Scales with the page, so A5 and A0 both look proportionally correct. |
| Text | One line, 40 characters | Defaults to CONFIDENTIAL. Latin glyphs only; the built-in font is Helvetica Bold. |
| Baking | Drawn into the content stream | The text becomes part of the page, so it appears in every viewer and in print. |
Five things people get wrong
Watermarking a document you still need to edit
The stamp is real text on the page. Producing a clean edited version afterwards means going back to the original.
Using a watermark as security
It is not. Any determined recipient removes it. Use password protection for access control.
Setting opacity too high
Above roughly 50 percent the stamp competes with the content and the document becomes hard to read.
Watermarking before the final approval round
You end up with watermarked text in the revised version. Watermark the copy you distribute; keep the master clean.
Using non-Latin text
The embedded font is Helvetica Bold with limited glyph coverage. CJK characters generally will not render.
Questions
Does it appear on every page?
Yes, every page of every file you add.
Can I change size or position?
Not in the free web version. The desktop version exposes size, opacity and position.
Is the text selectable?
Yes. It is drawn as real text into the content stream, so it can be selected and searched.
Does it work on a scanned PDF?
Yes, the stamp is drawn on top of the page image.
Can I use non-English text?
Partially. The embedded font has limited glyph coverage. Latin, Cyrillic and Greek mostly work; CJK generally does not.
Is the file uploaded?
No. All processing happens locally in the browser tab.
Does it increase the file size?
Marginally. The font is embedded once and the text is a few hundred bytes per page.
Need it without a browser tab?
PDFKit Desktop is a single offline file — no 10-file limit, page-range selection, per-page rotation, adjustable watermark, and it never needs a network connection. One-time $19, no subscription.
See PDFKit Desktop — $19