Verify a document
Check a signed PDF against the seal we recorded when it was completed. No account needed — don't take our word for it.
Check a file
The file never leaves this server's memory — we hash it and throw it away.
Or look one up
Paste a document ID or any of the hashes printed on a certificate of completion.
How this works
When every signer is done we flatten their input into the PDF and take a SHA-256 hash of it — that is the signed hash, and it is printed on the certificate of completion. We then append the certificate and hash the whole file again — the sealed hash. A certificate cannot carry the hash of a file it is itself part of, which is why there are two.
Change a single byte of either file — a word, a date, a pixel of a signature — and its hash changes completely and matches nothing here. That is what makes the seal tamper-evident.