Frequently Asked Questions

How does Satohash work?

Satohash hashes your file locally in your browser (SHA-256), then submits only that fingerprint to OpenTimestamps calendars, which anchor it into the Bitcoin blockchain. You get a portable .ots proof file plus a certificate.

Is it really free?

Yes — stamping is free today (REQUIRE_LIGHTNING=false). You pay no miners and no fees. Later there may be an optional Lightning fee to cover hosting, but the proof still anchors to Bitcoin.

Does my file leave my device?

No. Only a cryptographic hash (fingerprint) is transmitted. The original file never leaves your browser — zero-knowledge by design.

Is a Bitcoin timestamp legally valid?

Satohash proofs are designed to satisfy ESIGN Act (US), UETA (US), and eIDAS (EU) requirements. A Bitcoin timestamp is mathematically non-repudiable evidence of existence-at-a-time.

How long does confirmation take?

Typically within one Bitcoin block — about 60 minutes. Pending stamps upgrade automatically as calendars gather attestations.

What is OpenTimestamps (OTS)?

OpenTimestamps is a free, open-source protocol that anchors cryptographic fingerprints into the Bitcoin blockchain. It is calendar-based and independently verifiable.

Can I verify without Satohash?

Yes — use opentimestamps.org, the ots CLI, or any OTS-compatible tool. Your .ots file works forever, independently of Satohash.

What is NIP-05 identity?

Satohash supports Nostr NIP-05 identities (e.g. [email protected]) so you can attach a Nostr public key to your proofs.