Yes, adding watermarks to PDFs is completely free on PDFA2Z.

Can I control the opacity?

Yes, you can adjust transparency from 10% to 100% so the watermark is subtle or bold.

Free Add Watermark to PDF

Brand and protect your PDF documents with custom watermarks. Add "CONFIDENTIAL", "DRAFT", or your logo to every page with full control over size, position, and opacity.

Upload your PDF.
Choose text or image watermark.
Set position, opacity, and font size.
Download your watermarked PDF.

Is it free?: Yes, adding watermarks to PDFs is completely free on PDFA2Z.
Can I control the opacity?: Yes, you can adjust transparency from 10% to 100% so the watermark is subtle or bold.