Watermark PDFs with 5 text presets (DRAFT, CONFIDENTIAL, SAMPLE, COPY, VOID) or custom — font 12-160pt, opacity 5-100%, rotation -90° to +90°. Up to 5000 pages, no upload.
Watermarks signal intent visually — DRAFT, CONFIDENTIAL, SAMPLE — so a review copy is not mistaken for a final deliverable. OpenPDF ships 5 built-in presets (DRAFT / CONFIDENTIAL / SAMPLE / COPY / VOID) plus custom text, with font size 12-160pt, opacity 5-100%, rotation -90° to +90° and adjustable RGB color. Renders locally with pdf-lib across up to 5000 pages per document, auto-shrinking any text that overflows the page width — the watermarked PDF never leaves your browser.
A flattened watermark is baked into the pixels of the page and is hard to remove cleanly, but modern PDF tools can sometimes undo a text overlay. For strong protection, combine with a large opacity and place over the main content.
Yes, in addition to text. Upload a logo PNG (ideally with a transparent background) and position it with the same controls as text watermarks.
Yes. Choose a page range — all pages, a custom range, or specific individual pages.
No. Watermark rendering happens on your PDF locally in the browser.
OpenPDF is an independent project built around one principle: the PDFs you edit should never leave your device. Every tool — merge, split, sign, organize, annotate, compress, watermark, add page numbers — runs entirely in your browser using WebAssembly and modern JavaScript APIs. There is no upload step, no account, no email harvesting, and no premium tier gating the useful features. The codebase and the third-party scripts loaded for analytics and advertising are visible in the page source — Google AdSense and Google Analytics 4 load only after you accept cookies in the consent banner — so anyone can audit what is running before trusting the tool with sensitive contracts, scanned IDs, or financial documents.
By Marco B. · Last updated: