# Verify a signed PDF

Check whether a PDF is the exact file docuinked sealed. Your file stays in your browser. Only its fingerprint is sent, and no account is needed.

## How it works

Your browser works out the file's SHA-256 fingerprint on your own device, then sends only that fingerprint to us. We look it up among the documents we have sealed. If it matches, we tell you when it was sealed and how many signers it had. We never say who they were or what the document says.

## What a match means

A match means this file is byte for byte the same as the one docuinked sealed. That is all it means. It doesn't tell you who the signers really are, or whether the agreement is valid.

## What no match means

No match doesn't mean a document is fake. Saving or printing a PDF again changes its bytes, even if it looks the same. It could also be a test document, a deleted document, or one from another service. Ask the sender for the original file.

## Check it without us

The seal lives inside the file. You can open the PDF in Adobe Acrobat or a PDF validation tool and read the signature panel. To have it trusted there, add [our public certificate](/seal-certificate.pem). See [what a PDF seal proves](/guides/what-is-pades).

## Common questions

### Is my PDF uploaded?

No. The fingerprint is worked out in your browser with the Web Crypto API, and only that short string is sent. You can confirm this in your browser's network panel.

### Can someone learn about a document from its fingerprint?

Not without having the exact file. A fingerprint can't be turned back into a document, and the answer holds no names or content.

### Does this work for PDFs from other services?

No. It only knows documents docuinked sealed. Other services have their own tools.