💧PDF Utility

Watermark PDF Online Free
100% Private, In-Browser

Overlay custom text stamps with adjustable opacity, size, and rotation. Processed locally on your machine. Files never touch a server.

Choose a PDF file to watermark

or drag and drop your document here

Select PDF File
🔒100% In-Browser Privacy⚡Zero Server Latency♾️Unlimited Pages

Why Add Watermarks in Your Web Browser?

Watermarks are critical for safeguarding proprietary business plans, intellectual property, unreleased financial statements, and confidential client drafts from unauthorized sharing. Adding stamps like DRAFT, CONFIDENTIAL, or INTERNAL USE ONLY immediately signals sensitive status.

Unlike traditional web converters that require uploading your private documents to third-party cloud servers, FileConvert renders watermarks entirely inside your browser using pdf-lib. The document is stamped in your device's memory, ensuring your business assets remain 100% private.

Fine-Grained Opacity and Custom Styling

Enjoy full control over visual appearance. Adjust opacity to ensure text underneath remains crisp and readable, scale font size to suit any document layout, and choose between diagonal or horizontal stamps.

How It Works (Step-by-Step Guide)

1

Upload Document

Drag and drop your PDF into the upload zone to load your document.

2

Configure Watermark

Enter custom stamp text, choose font size, adjust opacity slider, and pick angle.

3

Apply & Download

Click Apply Watermark to embed the text overlay on all pages and download instantly.

Why Client-Side Matters

Experience modern client-side document processing with zero compromises.

⚡

Instant Processing

No network upload queues or waiting for server workers. Conversions begin immediately upon file selection.

🛡️

Bank-Grade Privacy

Your documents stay in your browser's sandboxed memory. No logs, no analytics on contents, zero server uploads.

♾️

Zero File Size Limits

Watermark massive multi-gigabyte or hundreds of pages without encountering arbitrary paywall caps.

📶

Full Offline Capability

Powered by Service Workers, this tool functions seamlessly even on airplanes or in secure offline air-gapped environments.

Frequently Asked Questions

Are my documents sent to a server to apply the watermark?

No. The watermark stamping executes 100% client-side inside your browser memory using pdf-lib. Your confidential records are never transmitted across the network.

Can I adjust the transparency so the underlying text remains readable?

Yes. Use the opacity slider to dial transparency between 10% and 100%. A 20% to 30% setting creates a subtle security stamp while ensuring full text readability.

Can I stamp diagonally across the whole page?

Yes. Choose the -45° Diagonal preset to create a prominent, anti-theft diagonal stamp spanning from corner to corner.

Does watermarking modify existing vectors or text in my document?

No. The watermark is rendered as an overlay content stream atop the existing page geometry, leaving all underlying text, images, and vectors completely intact.

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