PDF Watermark
Add text watermarks in your browser: tiled or centered, with size, color, opacity, rotation and page ranges. The result downloads automatically.
How to use
- Click the drop zone or drag in one PDF file. It is read locally and the page count shows up, with a warning above 200 pages.
- Type the watermark text. Only English letters, digits and common symbols are accepted; a warning means a character cannot be encoded.
- Adjust the font size, color, opacity and rotation, then pick tiled or centered layout.
- To watermark only some pages, fill in a range like 1-3,5. Leave it empty to process the whole document.
- Click "Add watermark and download". The result saves as
-watermarked.pdfand your original file stays untouched.
FAQ
Why is Chinese watermark text rejected?
Can the watermark be removed later?
Are my files uploaded to a server?
Can I watermark an encrypted PDF?
How do I watermark only some pages?
Screenshots
How to use
- Select a PDF file
Click the drop zone or drag a file in. The PDF is read locally, and the page shows the file name, size and page count. Your original file stays untouched.
- Enter the watermark text
Type what should appear on the pages, for example CONFIDENTIAL or DRAFT. Chinese is not supported yet; if a warning appears, switch to letters, digits or symbols.
- Adjust size, color and angle
The size starts at 48pt, the color at a medium gray, and 0.2 opacity suits most pages. A 45 degree angle is the classic diagonal, and 0 keeps the text horizontal.
- Pick a layout and page range
Tiling covers the whole page, while centering stamps it once in the middle. A range like 1-3,5 processes pages 1 to 3 plus page 5, and an empty range means every page.
- Generate and download
Click "Add watermark and download". When processing finishes, the browser saves a new file whose name ends with -watermarked, and the original PDF stays as it was.
About this tool
A text watermark overlays a short message on top of the page content. It is the quickest way to mark the status of a document. This tool lets you set the text, font size, color, opacity and rotation. Layout can be a tiled page or a single centered stamp. A page range narrows the work to selected pages. Everything runs inside your browser. The PDF is read, rewritten and saved locally. The result downloads automatically, and the original file stays exactly as it was. Because the watermark is written as vector text, it stays sharp when printed or zoomed, and the file grows only slightly.
Opacity controls how the watermark sits against the body text, and values between 0.1 and 0.3 keep it visible without blocking reading. Tiling fits drafts, internal handouts and any document that should be covered edge to edge, while a centered stamp suits covers and one-page statements. An angle between 30 and 45 degrees is harder to cover up than horizontal text and stays out of the way of the content. Light gray or pale red colors are the safest choices, because dark watermarks tend to bury the text underneath. When several files need the same settings, keep the page open and process them one after another.
How it works
This version draws watermarks with Helvetica Bold, one of the fourteen standard fonts built into the PDF format. Standard fonts carry no glyph data at all. The reader renders the shapes from the encoding, and that encoding is WinAnsi. Its table covers Latin letters, digits and Western symbols. Chinese characters sit outside the table, so pdf-lib throws an encoding error the moment it tries to write one. The tool checks the text character by character before generating and stops with a clear message instead of a broken file. This version keeps outputs light instead.
The watermark text becomes part of each page's content stream. The opacity value maps to the fill transparency parameter that readers blend with the content underneath. Placement math runs in display coordinates. The page's own rotation swaps the width and height first. The watermark center is then projected back into page coordinates. Portrait and landscape pages both get a correct diagonal. Tiling builds an even grid along the rotated direction, and the spacing scales with the font size. When a tiny font would create too many stamps, the grid thins out automatically, so multi hundred page files do not swell. The writer yields to the interface every 25 pages, so the tab stays responsive.
When to use it
- Mark contract drafts
Tile DRAFT across contracts and quotes still being negotiated. Recipients can tell at a glance that the file is not final. A light gray diagonal does not hide the clauses, stays readable in printouts, and keeps an oral version from circulating as the signed one.
- Internal handouts
Training slides, pay explanations and business data travel through group chats. A centered watermark with the company name or INTERNAL reminds readers where the file came from and what it is for. The mark still shows if the document is forwarded outside the team.
- Sample chapters and previews
Send sample chapters, reading previews or unpublished proposals with a watermark applied first. If the file is screenshotted and passed around, the mark travels with every page. That lowers the chance of the material being reused directly by someone else. The stamp also makes unfinished work obvious at a glance.
Tips & tricks
- For a quick test, put 1 in the page range and try sizes, colors and opacity on the first page before running the whole document.
- Tile spacing follows the font size, so larger text means wider gaps. Shrink the size one step if you want a denser pattern.
- A watermark is not a security feature, because people familiar with PDF tools can remove it. Pair it with password protection for sensitive files.
Things to watch
- Chinese text is rejected
The watermark font in this version only carries the WinAnsi encoding. Chinese characters and full width symbols cannot be written. The tool warns you before generating anything. Switch to an English abbreviation for now, or wait for a version with font embedding.
- Opacity set too low
Below 0.1 a watermark is nearly invisible on screen and disappears even more after scanning or printing. Keep marking watermarks at 0.15 or higher so the stamp keeps doing its job. Test one page before running a whole batch. Faint stamps give a false sense of protection.
- Dark colors bury the text
A large dark navy or black watermark sits on top of tables and paragraphs and makes reading painful. Treat the watermark as a hint: pick a low saturation gray or pale red, add a 45 degree angle, and the body text stays readable.