In short
This tool stamps a watermark on the pages of a PDF: “CONFIDENTIAL” on an internal document, “COPY” or “DRAFT” on a working version, a logo on a document sent to a client. The watermark is a text of up to 60 characters, accents, Greek and Cyrillic included, or a PNG, JPEG or WebP image of up to 20 MB. Set its layout (centred or tiled), its angle (diagonal or horizontal), its size, its opacity and, for text, its colour, then apply it to every page or to the first one only. It is added to the page content: an ordinary PDF reader cannot remove it. Several PDFs can be processed in one go. The processing happens in your browser.