Add Watermark to PDF

A PDF watermark is a semi-transparent label, usually text such as DRAFT, CONFIDENTIAL, or a company name, that is stamped across every page to signal a document's status or ownership. This tool draws that text directly into each page's content stream using the pdf-lib library, entirely inside your browser, so nothing is uploaded. You control three things: the watermark text, its opacity, and its rotation angle. A conventional draft stamp uses roughly 20 to 30 percent opacity at a 45-degree diagonal, which stays legible enough to read the underlying content while clearly marking it. Lower opacity is subtler; higher opacity is harder to ignore but can obscure text beneath it. It is important to be honest about what a watermark does and does not do. A watermark is a visual deterrent, not a security control. Because the text is painted into the page rather than locked, a determined person with a PDF editor could remove or cover it. For genuine restriction you combine watermarking with password encryption, which is a separate step. The watermark applies uniformly to all pages, which is exactly what you want for marking an entire contract or sample as DRAFT, but it means you cannot currently exempt a cover page. The font is a standard sans-serif, and the current version supports text only, not image or logo watermarks. Typical uses include circulating internal drafts, flagging sensitive files before they leave the building, branding shared documents, and marking client samples as PREVIEW before payment. Since the whole operation is local, even highly sensitive PDFs stay on your machine throughout.