Verify

Is this the real signed document?

Drop a completed PDF or certificate of completion here. We'll tell you whether it's byte-for-byte the file Signkoi sealed, or whether it has been changed.

Drop a PDF here

PDF up to 25 MB. We only calculate the file's fingerprint; the file is not stored.

How it works

What this check proves, and what it doesn't

When a document is completed, Signkoi seals the PDF and its certificate with a digital signature and records each file's SHA-256 fingerprint. This page compares your file's fingerprint with those records.

It proves

The file is byte-for-byte identical to the one Signkoi sealed when the document was completed.
Nothing in it has been changed since then: not a word, a signature or a page.
When it was completed, and when an independent timestamp authority confirmed the file existed.

It doesn't prove

Who the signers are. Their identities and the steps they took are listed on the certificate of completion.
That the document is legally valid or enforceable for your purpose.
Anything about a printout, a scan or a copy that has been edited, even slightly.