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 on this site — no BlockSign account required
- Or run the open-source verifier yourself — audit the algorithm end-to-end
Certificate of signature
v1DocumentMutual NDA — Northwind × Halcyon
SHA-256
Signer 17Hk2…aQ9F · Northwind Labs
tx
at2026-04-25T14:22:08Z
Signer 29pQr…vN3k · Halcyon Capital
tx
at2026-04-25T14:24:31Z
finalizedblock 287,449,102
Sealed