PDF tool
Watermark PDF
Add a text watermark to every page of a PDF in your browser. Mark documents as 'Draft', 'Confidential', or add your company name — the watermark is drawn diagonally across each page.
Your document is processed entirely on your device; nothing is uploaded.
Privacy & data handling
Browser processingThis tool processes your input locally in your browser. Nothing is uploaded to a server or sent to an external service.
Interactive tool
Watermark PDF
Choose files to process
Overview
What does Watermark PDF do?
This tool draws your watermark text across every page of the PDF at a 35-degree angle, in bold red at partial opacity, centered on each page. It is the classic diagonal watermark you see on drafts and confidential documents.
The watermark becomes part of the page's rendered content in the output file. It is visible when the PDF is viewed or printed, which is what makes it useful for marking documents before sharing.
This is a visible watermark for labeling documents — it is not encryption. To restrict who can open a file, password protection is the right mechanism.
Under the hood
How does it work?
The PDF is loaded in browser memory with pdf-lib. The tool embeds a bold font, then for every page draws your text as vector text on the page's content layer — rotated 35 degrees, centered vertically, in red at 35% opacity.
The result is saved as a new PDF with the watermark baked into each page's content. The file is offered as a download with a preview, so you can check how it looks.
All drawing happens locally in the browser; no copy of your document is sent anywhere.
Key features
Features of Watermark PDF
Use cases
When should you use Watermark PDF?
Marking drafts
Watermark a draft with 'Draft' so recipients know it isn't final before you share it.
Labeling confidential documents
Add 'Confidential' to internal documents that should not be redistributed.
Branding shared files
Add your company name so shared documents carry your branding.
Preventing casual misuse
A visible watermark makes it clear where a document came from and discourages unattributed sharing.
Step-by-step
How to use Watermark PDF
- Step 1
Upload your PDF file.
- Step 2
Enter your watermark text (e.g., 'Draft' or 'Confidential').
- Step 3
Choose position and opacity, then download.
Real example
Example
Your input
report.pdf (8 pages) Watermark text: CONFIDENTIAL
watermarked.pdf
Same 8 pages, each with 'CONFIDENTIAL' drawn diagonally across the page
The watermark is drawn on every page at 35° in bold red at partial opacity.
Technical information
How the details work
A PDF page's appearance is defined by its content stream — the drawing commands that paint text and graphics. Watermarking inserts additional drawing commands into that stream: here, bold Helvetica text rotated 35 degrees and drawn in red at 35% opacity, centered on the page.
Because the watermark is added to the content stream, it is part of the page: it displays and prints like any other text. It cannot be toggled off by the viewer, which is the point of a visible watermark.
Keep the original unwatermarked file if you may need to edit the document later — the watermark is baked in and is not cleanly removable from the output.
Privacy & security
Your data stays yours
Your PDF is watermarked entirely in your browser with pdf-lib. Nothing is uploaded or stored.
Local processing — files stay in your browser
- The file is parsed in browser memory — its contents never leave your device.
- The watermarked PDF is generated locally and downloaded directly.
- Nothing is retained after you close the tab.
- Analytics only record the page visit.
Limitations
What this tool does not do
- Text watermarks only — image watermarks are not supported in this tool.
- The watermark is baked into the output and not cleanly removable.
- Style is fixed: bold red text at 35% opacity, rotated 35°.
- A watermark labels a document; it does not prevent the file from being opened or copied.
- Very large PDFs are limited by browser memory.
Frequently asked questions
Common questions about Watermark PDF
Can I remove the watermark later?
The watermark is drawn into the page content of the output file, so it is not cleanly removable. Keep the unwatermarked original if you may need to edit the document later.
Is the watermark applied to every page?
Yes. The watermark text is drawn on every page of the document, centered and rotated at 35 degrees.
Can I change the color, size, or opacity?
The current version uses a fixed style: bold red text at 35% opacity, rotated 35°. The text itself is whatever you type.
Does a watermark protect my document from copying?
No. A visible watermark labels the document and deters casual misuse, but it does not prevent the file from being opened, copied, or edited. For access control, use password protection.
Are my files safe to watermark here?
Yes. Watermarking happens locally in your browser and your document is never uploaded.
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