Where a Company Seal Still Matters
In much of the world a company seal β the corporate chop in China, Japan, Korea and Taiwan, the official stamp across the Middle East, and the embossed or rubber seal still used by businesses in Thailand, Indonesia, India and parts of Europe and Latin America β is the organisation's mark of authority on a document. It signals that a quotation, invoice, purchase order, official letter or contract was issued by the company itself, not merely by an individual. As paperwork moves to PDF, the practical need does not disappear: counterparties, banks and government offices still expect to see the familiar seal on the page. Dropping a clean image of that seal onto the PDF is the digital equivalent of pressing the physical stamp, and for the vast majority of routine commercial documents it is exactly what is required.
A scanned seal works best as a PNG with a transparent background. Because the area around the circular or rectangular mark is see-through, the seal sits naturally over existing text β over a signature block, beside a date, or across the corner of a letterhead β without hiding the content beneath it. This tool lets you size the seal anywhere from a small initial-style stamp up to half the page width, and place it precisely by clicking the exact spot on a live preview of the page.
How In-Browser Sealing Keeps Your Documents Private
When you choose a file, the browser's File API reads it into an ArrayBuffer β
a raw byte sequence held in memory inside the page's sandbox. Nothing is sent to a server, because
no server participates: the application is static HTML and JavaScript. The
pdf-lib library parses the document
into its internal object graph, and your seal image is registered as an image XObject with its
alpha channel preserved, so the transparent areas of the stamp stay transparent on the page.
The spot you click on the preview is mapped from canvas pixels into PDF user space β a coordinate
system measured in points (1/72 inch) with its origin at the bottom-left of the page β which is why
the tool flips the vertical axis before writing the placement. Then
doc.save() re-serialises the whole
object graph into a brand-new file, assembled entirely in the local sandbox and handed to you as a
download. The original file on your disk is never modified, and a preview of the finished page is
rendered for you to check before you download. The only network traffic in the entire process is the
one-time, cacheable download of the open-source libraries β your document bytes never appear in any request.
Seal, Signature, or Both?
A seal represents the organisation; a signature represents a person. Many documents carry both β an authorised signatory signs, and the company seal is applied alongside to show corporate endorsement. You can combine the two here: use the Sign PDF tool to add the handwritten signature, then this tool to stamp the seal exactly where it belongs. Because each step writes a complete new file locally, you can layer as many marks as you need without ever uploading the document.