Check a redaction certificate
Someone sent you a redacted PDF and a certificate. This confirms the two belong together — that the file in your hands is the exact one the certificate describes, unchanged since it was made.
You don’t need an account, and you don’t need to trust us: the check is a SHA-256 comparison that happens in this tab. Neither file is uploaded — open your Network tab and watch if you like.
The redacted PDF
The file you were sent
The certificate
The .json that came with it
What a match does and doesn’t prove
It proves the PDF you have is byte-for-byte the file the certificate was issued for, and it shows what was redacted from it — which pages, how many areas, and whether any selectable text survived on those pages.
It doesn’t prove when the redaction happened or who did it. The time comes from the issuing device’s clock, and there is no third-party signature, because obtaining one would mean sending something about the document to a server. That was the trade we made deliberately.
A mismatch is worth taking seriously but isn’t automatically sinister — re-saving a PDF in another application rewrites the file and changes its fingerprint, even when the visible content is identical.