Add Custom Text Watermark to PDF

Beyond "DRAFT" and "CONFIDENTIAL", many organizations use custom watermarks: a company name, a contract reference number, a recipient's name ("Prepared for Acme Corp"), or a copyright notice. This tool accepts any text as the watermark.

Type your watermark text in the input field, configure the font size and opacity, and apply it to every page of your PDF. The watermark is rendered diagonally across the center of each page using Helvetica — a universally available font that reads clearly at various sizes and opacities.

Custom watermarks are also useful for versioning — watermarking with "Rev 2 — 2025-05-01" makes it easy to identify which version of a document someone is reading, even if they save a copy locally.

No upload. Everything runs in your browser with pdf-lib.