EXPLAIN
Validation, lookup, generation and QR rendering all run locally. There is no API call, no account, no analytics and no cookie banner, because there is nothing to consent to. Account numbers you paste stay on this page.
Every IBAN is checked three ways: the country's registered length and structure from ISO 13616, the mod-97 check digits from ISO 7064, and — for 28 countries — the domestic check-digit scheme the country's own banks use.
Country rows follow the ISO 13616 registry. SEPA membership follows the EPC's published scope. Where a source disagrees with a live service, the official source wins: publishing a known-stale fact would be the worse error.
Every figure on this site is computed, not described. Check digits, field splits, masks and payloads come from the same code that is tested against 392,400 accounts for Germany alone.