PDF Watermark
Stamp every page with text you choose. Tiled or in one position, over the content or underneath it.
Drop a PDF here
Nothing is uploaded. The file is read in this page.
Only used in tiled mode. Percentage of the text's own width.
Paints the mark under the text and images so the body stays crisp.
The preview shows page one with the watermark applied.
Everything here runs on your device. Nothing you enter is uploaded or stored.
Stamp text across every page of a PDF: tiled for full coverage or a single mark in one of five positions, at any size, angle, opacity and colour, drawn either over the page content or behind it. Page one previews live as you adjust.
How to use it
- Drop or choose the PDF you want to watermark.
- Type the text — DRAFT, CONFIDENTIAL, a client name, a date.
- Pick tile mode or one of the five single positions.
- Adjust size, angle, opacity and colour; the preview updates as you go.
- Tick “Draw behind content” if the mark should sit under the text.
- Press Save to download the watermarked PDF.
Drawing behind content, and why most browser tools cannot
A PDF page’s content is an ordered array of instruction streams, painted in array order — later streams paint on top of earlier ones. Every PDF library that draws on an existing page appends its instructions to the end of that array, which is why browser watermark tools almost universally stamp over the content only: appending is the entire API surface they have.
The array is still an array, though. Once the mark has been drawn, moving that one stream from the end to the front makes exactly the same instructions paint first, and therefore underneath everything else. Nothing about the mark changes; only when it is painted does. That single reordering is what the “behind content” option does, and it is why the text on a dense page stays perfectly sharp while the watermark still shows through the white space.
Tiling that actually covers the page
Rotate a line of text 45 degrees and it no longer fits inside the rectangle it occupied at zero degrees — it sweeps out past two opposite corners. A tile grid laid out to the page’s own width and height therefore leaves conspicuous empty triangles in the corners the moment the angle is non-zero, which is the single most common flaw in tiled watermarks.
The grid here starts one full step outside the page on both axes and runs one step past the far edge, so every corner is covered by a mark whose origin sits off-page. Those overhanging tiles are clipped by the page boundary at no cost. There is a hard cap of 4,000 marks per page, which is far past the point where more tiles are visible, so an extreme size-and-gap combination cannot turn into a browser hang.
What it does not do
It stamps text, not images — an image watermark on a PDF is a different job and needs a different tool. It does not protect anything: a watermark is page content and anyone with a PDF editor can remove it, which is true of every watermarking tool that exists. It uses Helvetica Bold, a font built into every PDF reader, so output stays small and renders identically everywhere — but that font cannot encode Cyrillic, Greek, CJK or emoji, and those characters will not appear.
Settings and what they are for
| Setting | Use it to |
|---|---|
| Tile mode | Cover the whole page so no region is unmarked |
| Opacity | Keep the mark readable without burying the text |
| Angle | Make the mark obviously an overlay rather than page content |
| Behind content | Keep body text perfectly crisp on dense pages |
| Colour | Match a house style, or go pale grey for a subtle mark |
Questions
What is the difference between drawing behind and over the content?
A watermark drawn over the content sits on top of the text and images, so at any noticeable opacity it slightly obscures what is underneath. Drawn behind, it is painted before the page content, so the text stays perfectly crisp and the mark shows through only in the white space. Behind looks more like a printed letterhead and reads better on dense documents; over is the right choice when the watermark needs to be unmistakably in the way, such as a proof copy that must not be mistaken for final.
Why does tile mode place marks partly off the page?
Rotated text sweeps outside the box it would occupy unrotated, so a tile grid sized exactly to the page leaves visible bald patches in the corners at any angle other than zero. The grid deliberately starts one full step outside the page on both axes and runs one step past the far edge. The tiles that fall outside are simply clipped by the page boundary, and the result is even coverage right into the corners.
Can the watermark be removed by whoever receives the file?
Yes, by anyone with a PDF editor, and this is true of every watermarking tool including expensive ones. A watermark is page content, not protection — it marks provenance and intent, it does not enforce them. If a document genuinely must not be altered, that is a job for a digital signature, and if it must not be copied, no watermark of any kind will achieve it.
Which fonts and characters are supported?
The watermark uses Helvetica Bold, one of the fonts every PDF reader is required to have built in, which keeps the output small and guarantees it renders identically everywhere. That standard font covers Latin script and common punctuation. Characters outside its range — Cyrillic, Greek, CJK, emoji — cannot be encoded in it and will not appear.
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