Validate any IBAN deterministically: ISO 13616 mod-97 checksum, country + length registry check, BBAN and bank-code extraction, canonical formatting. Zero external dependencies, no hallucination, always available. Use it to validate a bank account before initiating a SEPA/international payment. Ed25519-signed. 0.001 USDC on Base. First 3 calls FREE per wallet — send header X-WALLET: 0x<your Base address> (no payment); then per call.