Add custom text watermark to PDF pages
Last updated: 2026-10-08
Add Watermark is a free online tool that overlays custom text diagonally across the center of every page in a PDF, with an adjustable opacity slider ranging from 10 percent (very faint) to 100 percent (solid) for controlling visibility. It's commonly used to mark draft documents, indicate confidentiality, or brand documents before sharing externally. Currently only text watermarks are supported; image or logo watermarks are not yet available. Processing happens entirely client-side using pdf-lib, so the source document is never uploaded to a server. There is no file-size limit and no cap on the number of pages watermarked in one operation. The tool requires no account or software installation, and works identically across desktop and mobile browsers, producing a downloadable watermarked PDF within seconds of entering the watermark text and adjusting its opacity to the desired level.
The watermark is placed diagonally across the center of each page for maximum visibility.
Currently only text watermarks are supported. Image watermarks are coming soon.
Yes. Use the opacity slider to set transparency from 10% (very faint) to 100% (solid).
Yes, all 32 tools are 100% free forever. No hidden charges, no premium version, no login required.
No. We have zero file size restrictions. Process any PDF of any size, as many times as you want.