Watermark PDF

A watermark has exactly one job: communicate status or ownership at a glance without destroying readability. The three variables are wording, visibility, and coverage. Wording should be one or two words — CONFIDENTIAL, DRAFT, SAMPLE, or your company name — because sentences become visual noise. Visibility lives in the 10-30% opacity band: below it the mark is ignorable, above it the document becomes work to read. Coverage is the diagonal-versus-tiled decision: a single center stamp suits internal review, while tiled repeats suit anything leaving the building.

Color choice matters more than people think. Mid-gray disappears on charts but survives printing; red screams urgency yet can obscure red ink in financial tables; dark navy reads as official but fights with body text. Our preview exists precisely so you can test these combinations against your actual pages instead of guessing — check the busiest page of your document, not the emptiest one, because worst-case legibility is what counts.

A watermark is simply extra content drawn on top of each page: text rendered with an embedded font at low opacity, or an image stamped at a computed position and scale. Our tool embeds Helvetica Bold once (for text mode) or your uploaded PNG/JPG (for logo mode), then draws it onto every page with pdf-lib, entirely in your browser. Rotation is applied around each mark, and tiled mode steps across the page in a grid so coverage stays even on mixed page sizes.

Because watermarking only adds a content layer, everything underneath — text selectability, vector sharpness, hyperlinks, form fields — is preserved byte-for-byte. The trade-off to understand is permanence versus security: the mark prints, merges, and compresses along with the file, but a visible watermark is a deterrent, not encryption. Anyone with a PDF editor can overlay or crop around it, which is why sensitive distribution should combine watermarks with proper access controls.