Seal anything.
Prove it is unaltered.
Turn a file or a note into a small, self-contained proof. Anyone can check that it is unchanged, offline, on any device, with no account and no trust in us.
Ed25519 · SHA-256 · Merkle · no server, no account, no expiry
- Datayour file or note
- SHA-256accb14f388…9a4998
- Merkle rootf6fa2cd005…b1980e
- Ed255199c2f7a41d8…0b8e31
- Checkpointsigned · verifiable offline
Evidence you can hold, and check yourself.
A seal is a small, self-contained bundle. It proves the data inside is exactly what was sealed and has not changed since. The proof is pure math, so it does not depend on us being online, in business, or trusted.
- 01
Seal
A fresh key signs your data in your browser, then is discarded. Your file and your key never leave the page.
- 02
Share
You download one portable bundle. Send it however you like; it carries its own proof inside.
- 03
Verify
Anyone checks it with the open offline verifier. No network, no company, no expiry.
What a seal proves. And what it never claims.
Honesty is the product. “Verified” means cryptographically unaltered and matching the seal. It never means “true.”
- The data is unchanged since it was sealed.
- It matches the seal, exactly.
- The committed time the seal was made.
- It was sealed by the holder of a signing key.
- That the sealed claims are true.
- Who the sealer is (the key is anonymous here).
- Physical presence, or that a real-world event happened.
- That nothing was left out.
Seal something now.
It takes a few seconds, costs nothing, and the proof outlives us.
Seal something