Validate a single International Bank Account Number (IBAN) against the official ISO 13616 structure for its country.
What it checks: the country code, total length for that country, the national BBAN structure, and the MOD-97 check digits. When the bank/branch code maps to a known institution, the response also includes the bank name, BIC/SWIFT code, and country.
Returns JSON with `valid` (boolean), `iban`, `formatted`, `country`, `country_name`, `check_digits`, `bban`, and, when the bank is recognized, `bank_name`, `bic`, `bank_code`, `bank_city`, `sepa` and `national_check_valid`. An invalid IBAN still returns a result, with `valid: false`, an `error` message and an `error_code` (e.g. INVALID_CHECKSUM, INVALID_LENGTH, UNKNOWN_COUNTRY); it does not throw.
Use this when you have one account number to verify. For many IBANs prefer `validate_bulk_ibans`; to pull IBANs out of prose use `extract_ibans_from_text` first. No account data is stored; validation runs in memory and is discarded. Requires an API key; a free key from ibanchecker.cash/api-docs covers 100 requests a month.