Say what a document is before anyone reads it
A proposal sent without markings tends to travel: forwarded, printed, quoted back at you months later as if it were final. A diagonal DRAFT across every page prevents that misunderstanding. CONFIDENTIAL on a price list reminds the recipient it wasn't meant for their competitor. Agencies watermark concept work with their name so unpaid drafts aren't quietly used. The common thread — these are exactly the sensitive files that shouldn't be uploaded to a random server to get stamped.
Three layouts, adjustable weight
Diagonal places one large stamp corner-to-corner across each page — the classic look. Horizontal centers the text straight across the middle. Tiled repeats it in staggered rows over the whole page, the pattern used when cropping a single stamp out must not be possible. Opacity runs from a barely-there 5% to a hard-to-miss 60%, in gray, red, or blue, at three sizes. The watermark is drawn as vector text with the PDF standard's built-in bold font: pages aren't re-rendered, the document's own text stays selectable, and the file barely grows.
An honest note on what a watermark does
A watermark communicates status and deters casual reuse — it is not copy protection. Someone determined, armed with editing software, can remove a stamp from a PDF, just as they could retype the document. For layered protection, combine it with the Protect PDF tool on this site to add a password. And because the whole process runs in your browser, neither the document nor your watermark text is transmitted anywhere — no account, no daily cap, no charge.