How to Add a Watermark to a PDF — CONFIDENTIAL, DRAFT and Custom
Watermarks protect documents, indicate their status and assert ownership. Here’s how to add a professional watermark to any PDF — completely free.
Thank you for reading this post, don't forget to subscribe!What are PDF watermarks used for?
Watermarks serve several distinct purposes:
- Status indication — DRAFT on a document that isn’t final; SAMPLE on a template shared for preview
- Confidentiality marking — CONFIDENTIAL on sensitive internal documents
- Void/invalid — VOID on a cancelled invoice; SUPERSEDED on an outdated version
- Branding — company name or website URL on shared proposals and reports
- Copyright — photographer’s name or studio watermark on proofs
How to add a watermark on CuroPDF
Go to curopdf.com/watermark-pdf
Opens in any browser — no signup needed.
Upload your PDF
Select the document to watermark.
Enter your watermark text
CONFIDENTIAL, DRAFT, SAMPLE, your company name…
Configure appearance
Choose size, color, opacity and position.
Click Add Watermark Now
Applied to every page in your browser instantly.
Download
Watermarked PDF ready to share.
Choosing the right opacity
- 10% — Very light: barely visible, suits high-end proposals where discretion matters
- 20% — Light: professional standard. Clearly visible but doesn’t dominate the content
- 35% — Medium: unmistakable. Use when recipients must notice the watermark
- 50% — Bold: dominant. Use for VOID, CANCELLED or documents you want clearly marked
💡 For CONFIDENTIAL documents sent to clients, 20% grey diagonal is the professional standard. It’s clearly visible but not distracting.
Color guide for different purposes
- Grey — neutral, professional. Works for any status mark.
- Red — urgency. Use for VOID, REJECTED, CANCELLED, URGENT.
- Blue — corporate. Use for company names and branding watermarks.
- Black — formal. Use at low opacity for subtle branding.
After watermarking
Consider also password protecting the document so recipients can view but not modify it. For very sensitive documents, combine watermarking with redaction to remove specific data before sharing with external parties.