IBAN-validator och generator

An IBAN — International Bank Account Number — is the standardised way to identify a bank account across borders in Europe and beyond. Behind every IBAN sits a small mathematical safeguard called the MOD-97 checksum: two digits placed right after the country code that prove the rest of the number was typed correctly. If a single digit is wrong, the checksum no longer matches and the IBAN is rejected by every bank in the world. That is why pasting an IBAN into a validator before initiating a transfer is the cheapest insurance against typos that send money to the wrong account.

The validator on this page does the full check in your browser. It verifies the MOD-97 checksum, then matches the country-specific structure (Germany has an 8-digit Bankleitzahl plus a 10-digit account number; France adds a national check digit; the Netherlands uses a 4-letter bank code) and finally cross-references the bank-code portion against a curated database of major European banks. Where a match is found you also see the BIC/SWIFT code needed for international transfers — saving a separate lookup on the bank's website.

The Generate tab solves the inverse problem: given a country and the local BBAN (the part of the account number that exists in the bank's own systems), it computes the two MOD-97 check digits and assembles a fully valid IBAN. This is useful when migrating from a national account format to the IBAN format, when populating a test fixture for accounting software, or when verifying that an IBAN you were given matches the underlying account number you have separately. Both modes are 100% client-side: nothing is uploaded, nothing is logged, no account is required.