On-chain proof
Don't trust us. Verify the chain.
Every signed BlockSign document carries its own receipt. Hand the PDF to a counterparty, a court, or an auditor and they can confirm authenticity against Solana directly — no BlockSign account, no API key, no trust in us required.
What the receipt actually contains
- SHA-256 document hash committed to Solana every signed version
- Each signed version recorded as a separate on-chain memo transaction
- Tamper-evident: a single byte change invalidates the document hash
- Free verifier — drop a signed PDF in, no BlockSign account required
Certificate of signature
v1DocumentMutual NDA — Northwind × Halcyon
SHA-256b3a1f72c9e441d08…74af2c1e
Signer 17Hk2…aQ9F · Northwind Labs
tx5xK9p3HFqB2nL7vWmYz…8sJk
at2026-04-25T14:22:08Z
Signer 29pQr…vN3k · Halcyon Capital
tx3qPm9DvR4xT6yWnLkQs…aBcD
at2026-04-25T14:24:31Z
finalizedblock 287,449,102
Sealed