Prove a file existed at a certain time
Get an independent, signed timestamp for any file. Your file stays on your device: only its fingerprint (a SHA-256 hash) is sent.
Choose a file
or paste a SHA-256 hash you computed yourself
Your file's fingerprint
Stamping sends only the hash above. The hash, the time and the stamp are published in the public log so anyone can check them later. A hash does not reveal your file's contents, but anyone who already has the same file can tell it was stamped.
Stamped
What you get
- A signed timestamp token (
.tsr) in the international RFC 3161 format, which standard tools such as OpenSSL can check. - A public record of the stamp in an append-only log, so the time cannot quietly be changed later, not even by us.
- An evidence package (
.zip) with the token, certificates, log proof and step-by-step instructions, so anyone can check the stamp without relying on this website.