Austria’s IBAN is compact and fully numeric, which tempts teams to skip dedicated fixtures and reuse German ones. That shortcut breaks quickly: an Austrian test IBAN is 20 characters, not 22, structured as AT, two mod-97 check digits, a 5-digit Bankleitzahl and an 11-digit account number with leading-zero padding. Any per-country length table, input mask or formatting helper will treat AT and DE differently, so your test data must too.
What validators actually check for AT
Three layers, in practice: total length of 20, an all-digit BBAN of exactly 16 digits, and correct ISO 7064 mod-97-10 check digits. Austria does not define a single national check-digit algorithm inside the BBAN; banks use their own internal schemes for account numbers, which is why format plus checksum is the practical bar for test data. The generator on this page meets it, defaulting to documented example bank codes so output is recognisable as synthetic, and stamping every value with a TEST label.
A QA angle: the grouped-display problem
Austrian IBANs are conventionally displayed in groups of four: AT61 1904 3002 3457 3201 style. A surprising number of bugs live in the gap between stored form (no spaces) and displayed form (grouped). Good end-to-end tests paste both variants into your form and assert both are accepted and normalised. Generating a few distinct AT IBANs here gives you the raw material; your Cypress or Playwright test handles the paste variations. Everything is generated client-side in the browser, with no server round-trip, logging or storage.
Sandboxes and the existence question
Payment-provider sandboxes for the Austrian market accept these values wherever a syntactically valid IBAN is required, for instance when creating SEPA Direct Debit mandates in test mode. But formal validity is a property of the string, not of the world: no account exists behind any generated IBAN. With Verification of Payee active for euro payments in the EU, banks match recipient names to IBANs before money moves. Keep test IBANs strictly in test systems, never on invoices, payment requests or anything presented as real bank details.