Add Watermark to PDF Online — Free PDF Watermark Tool

Watermarking is a soft form of document control. It does not encrypt or restrict access, but it makes the status of the document visually obvious to anyone looking at it. A DRAFT watermark tells a reader the document is not final. A CONFIDENTIAL watermark warns that distribution is limited. A faint company logo across every page signals authorship.

Watermarks are also useful for tracing leaks: a small recipient identifier — initials, email, or client name — stamped on each copy makes it possible to identify the source if the PDF is later shared without permission.

pdf-lib opens the source PDF and exposes each page for drawing. For text watermarks, the tool embeds a standard font, calculates centre positioning based on page dimensions, applies opacity and rotation, and draws the text on top of existing content. For image watermarks, the uploaded PNG or JPG is embedded as a PDF image XObject and placed at the chosen position with the chosen scale.

Because the original page content is left untouched and the watermark is layered on top, the underlying PDF text remains fully selectable, and any embedded images keep their original quality.

Use a low opacity (15–30 percent) for diagonal full-page text watermarks so they do not interfere with reading the document.

Use a higher opacity (60–90 percent) for small corner logos that should be clearly visible without obscuring text.

Diagonal text at 45 degrees across the centre of the page is the most universally recognisable watermark style — use it for DRAFT and CONFIDENTIAL.

If you are stamping a logo, prepare the image with a transparent background (PNG) so the watermark blends cleanly with the underlying PDF content.

Watermarked documents are often the most sensitive ones — drafts of contracts, internal strategy documents, client deliverables. iLoveeIMG handles watermarking entirely in the browser. The PDF and any watermark image you upload never leave your device.

Closing the tab discards everything from memory, and no log of the operation is kept anywhere.