Add Watermark to PDF
Stamp confidential badges, company logos, and security watermarks onto your documents with live angle and opacity control. Zero cloud uploads.
Drop your PDF, type your watermark text or choose an image stamp, adjust opacity and angle, and bake the watermark directly into the PDF content streams in RAM: Drop your PDF, type your watermark text or choose an image stamp, adjust opacity and angle, and bake the watermark directly into the PDF content streams in RAM.
Drop your PDF document here
Or click to browse from your device. 100% in-browser private execution.
How Client-Side PDF Watermarking Works
LocalDoc embeds vector text fonts and alpha graphics state dictionaries (/ExtGState) into your PDF pages in browser RAM, ensuring security badges cannot be removed by simple copy-paste while maintaining high print clarity.
Read Full Watermark Guide →Why Watermark PDFs with LocalDoc?
Fully Customizable
Control watermark text, font size, opacity, rotation angle and position. Add diagonal "CONFIDENTIAL" stamps or subtle copyright notices with full precision.
Private Processing
Confidential documents stay confidential. Your PDF is modified in browser RAM — not uploaded to any server. Ideal for legal, HR and financial documents.
All Pages at Once
The watermark is applied to every page simultaneously. No need to stamp pages one by one — upload, configure and download in seconds.
Live Preview
See exactly how your watermark will look before downloading. Adjust opacity and position in real-time with the interactive mockup preview panel.
Common Watermark Use Cases
- DRAFT / CONFIDENTIAL — Mark internal reports, contracts and proposals before sharing for review.
- Copyright protection — Add your company name or © notice to creative documents, portfolios and presentations.
- SAMPLE / VOID — Clearly label sample documents, invoices or certificates to prevent misuse.
- Reviewer copy tracking — Add recipient names to shared documents to track distribution.
Frequently Asked Questions
Can I remove a watermark I added using this tool?
Once applied and downloaded, the watermark is baked into the PDF as a permanent page element. To modify it, you would need to re-watermark the original PDF. Always keep a copy of the unwatermarked original.
What opacity level looks best for a diagonal watermark?
For diagonal watermarks like "CONFIDENTIAL", an opacity of 15–25% is typically ideal. It remains clearly visible on screen and in print while keeping the main content readable underneath.
Is the watermarked PDF compatible with Adobe Acrobat?
Yes. The output is a standard ISO 32000-compliant PDF file, compatible with Adobe Acrobat Reader, Preview on Mac, and all major PDF viewers on any platform.
Can I add an image watermark instead of text?
The current version supports text watermarks with full customization of font, size, colour, opacity and rotation. Image watermark support is planned for a future update.
Related Document Tools
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PDF Watermark Tool — Engineering & Legal Standards
Frequently Asked Technical Questions
Real-World Performance Benchmark
Tested by Amaad Mazari on: Tested on Chrome 124 / macOS Sonoma