Add Watermark to PDF Online
Stamp custom text watermarks across your PDF documents. Customize text, diagonal or horizontal angle, opacity, color, and font size in seconds.
Select or Drag a PDF to Add Watermark
Stamp diagonal or horizontal text watermarks (e.g. CONFIDENTIAL, DRAFT) across all pages with customizable opacity and font size.
Frequently Asked Questions
How do I add a diagonal watermark like "CONFIDENTIAL" to my PDF?
Upload your PDF, type or click the preset "CONFIDENTIAL", set the position to "Diagonal Center (45° Angle)", adjust opacity (25% recommended for readability), and click Apply. You can download the stamped PDF immediately.
Can I change the transparency of the watermark so it does not block text?
Yes. SizeSnap provides an opacity slider ranging from 10% (subtle background watermark) to 80% (bold security stamp), ensuring your underlying document text remains legible.
Can I exclude the watermark from the cover page?
Yes. Check the "Do not watermark the first page (Cover / Title Page)" option, and SizeSnap will apply the stamp only from page 2 onward.
Are my confidential documents uploaded to any remote server?
No. All watermark rendering happens entirely client-side inside your browser sandbox. Your sensitive files, proposals, and contracts never touch an external server.