Proof of existence

Compute a SHA-256 fingerprint of a file or text. Nothing is uploaded. Download a certificate recording the hash and time.

or paste text

SHA-256

The seal is drawn from the hash: any change to the content gives a different seal, so you can compare two versions at a glance.

Verify

Choose the file and the certificate you downloaded earlier. Nothing is uploaded.

FileCertificate (.json)

Note: the timestamp here comes from your device clock. For independent, third-party proof, anchor the hash publicly (e.g. OpenTimestamps) — a good next step for this tool.