Build a stable SHA-256 fingerprint from a normalized phone, email, zip and product/service type, for detecting the same contact submitting more than once. Normalization only (digits-only phone, lowercased trimmed email); does not look up or store anything.
| Network | Scheme | Amount | Pay To |
|---|---|---|---|
| Base | exact | $0.01 USDC | 0x421b...a89e |