PDF Watermark
Stamp a diagonal text watermark across every page.
Overview
The PDF watermark tool stamps a diagonal text watermark across every page of a PDF — "DRAFT", "CONFIDENTIAL", a date, a recipient's name, or any custom string. The watermark is placed behind the visible content with light opacity so the underlying document remains readable but the mark is unmistakable.
Legal teams marking drafts, finance teams flagging unaudited statements, and sales staff stamping recipient names onto distributed proposals reach for this when a printed-and-stamped look is needed without the printer. Long-tail searches that lead here include "add diagonal watermark to PDF", "watermark every page of PDF", and "stamp CONFIDENTIAL on PDF online".
How it works
A PDF page's content stream supports arbitrary graphics operators including text drawing with rotation. The watermark tool prepends a new content stream to each page that switches to a chosen font (a standard PDF base font, so no extra embedding is needed), applies a rotation transform (typically 45°), sets a grey fill colour with reduced alpha, and emits the watermark text positioned at the page centre.
Because the watermark is drawn before the original content stream, the existing page content renders on top and remains crisp. Page dimensions and orientation are read from each page's media box so the watermark stays centred and the text size scales sensibly across A4, letter, legal, or unusual sheets.
Examples
- Stamp "DRAFT — DO NOT DISTRIBUTE" on every page of a contract before review.
- Add a "CONFIDENTIAL" mark to a board-meeting handout.
- Apply a recipient's name to a personalised proposal copy.
- Mark a financial report as "UNAUDITED" until the audit is signed off.
FAQ
Can the watermark be removed?
A determined recipient with a PDF editor can erase a content-stream watermark, since this is not a security feature. For tamper resistance, use a digital signature or a flattened raster output.
Is the watermark searchable?
It is real text, so yes — copy and search work normally. Use a non-text image watermark only when text searchability is undesirable.
Will it look right on landscape pages?
Yes. The mark is centred and sized to the page's actual width and height, so landscape, portrait, and mixed-orientation documents all watermark cleanly.
Does it support coloured watermarks?
A light grey is the default for readability. Other colours are possible but very dark watermarks tend to obscure the underlying content and are usually counterproductive.
Can I watermark only some pages?
The standard mode stamps every page. To watermark a subset, split the PDF first, watermark the desired range, and merge the parts back together.