- Is my PDF uploaded to a server?
- No. Everything runs in your browser using JavaScript. Your PDF bytes are read locally by the File API, processed by pdf-lib running in your browser tab, and the resulting file is downloaded directly to your device. No data is transmitted anywhere.
- What is the difference between a stamp and an annotation?
- PDF annotations (including "stamp" annotation objects) are a metadata layer that can be removed, hidden, or stripped by a PDF editor in seconds. The stamps this tool creates are written as permanent vector content directly into the page's content stream — just like the original text and graphics — and cannot be removed without specialized editing tools. This makes them appropriate for approval workflows, invoicing, and records management.
- Can I stamp multiple pages at once?
- Yes. Use the page toggle buttons in Step 2 to select which pages get stamped. Tap "All" to stamp every page. Each page receives the stamp at the same relative position (as a fraction of page width and height), so it lands consistently on every page regardless of size.
- What font does the stamp use?
- The stamp uses Helvetica Bold, which is one of the 14 standard built-in PDF fonts. No font file is embedded, keeping file size minimal. The text is drawn in outlined/filled vector form, so it prints crisply at any DPI.
- Does the stamp work on password-protected PDFs?
- No. If a PDF has owner-level encryption that restricts content modification, pdf-lib will be unable to modify the page content stream. Open the file in Preview or Adobe Acrobat, remove the password, and then stamp it here.