APN File Verify

Give any file a fingerprint today. Prove it hasn't changed tomorrow.

Nothing leaves your device. Hashing runs in your browser via Web Crypto. No upload, no account, no tracking. This page works offline — save it and keep it.

You can select more than one file — each gets its own seal record.

Stored in the seal record only — remember, the note is your claim, not proof.

What this tool proves — and what it doesn't

  • Integrity, not identity. A matching hash proves the bytes are unchanged — not who made the file, and not that its contents are true.
  • Tamper-evident, not tamper-proof. APN File Verify detects change; it cannot prevent it.
  • The timestamp is your device's clock, recorded in the seal — it is not an independent, certified time source.
  • Keep the seal record safe. Anyone holding both the file and the record can verify; without the record there is nothing to check against.
  • APN File Verify v0.1 is an information tool — not legal advice, not a notary, not a government service.