Add a watermark to a PDF

SwiftPDFEdit's Watermark PDF tool draws custom text across the pages of a PDF — a single diagonal stamp or a repeating tiled pattern — with full control over size, colour, angle and opacity. The watermark becomes part of the page content, so it appears in every viewer and on every printout.

A watermark communicates a document's status before anyone reads a word. DRAFT stops a working version being quoted as final; CONFIDENTIAL sets expectations about forwarding; SPECIMEN or SAMPLE keeps a template from being mistaken for a real instrument; a company name across a shared design or proposal makes casual reuse awkward and attribution obvious.

The controls exist because the right watermark depends on the document. Opacity is the setting people most often get wrong: light enough to read through, dark enough to be unmissable — somewhere around 15–30% suits most text documents, and a low-contrast colour such as grey or muted red is easier to live with than solid black. A 45° angle across the page is the classic diagonal stamp; the tiled layout covers the page with repeats, which is harder to crop out of a screenshot. You can also restrict the watermark to specific pages, which is useful for marking exhibits or appendices while leaving the cover clean.

Because the watermark is drawn into the page's content stream rather than added as an annotation, it cannot be toggled off in a PDF reader or deleted from the layers panel. That is the point — but it also means the operation is one-way, so always keep an unwatermarked master copy. There is no “remove watermark” for a stamp that has been merged into page artwork, here or anywhere else.

Everything runs on your device. Legal drafts and financial statements are exactly the documents most likely to need a CONFIDENTIAL stamp, and they should not be uploaded to a stranger's server to get one.