IBAN validator

An IBAN is a country code, two check digits and the country's own account number — the account part, or BBAN. The page checks three things, in the order a bank would. The country code must be one that issues IBANs; the whole thing must be exactly the length that country uses, 22 characters for Germany and the UK, 27 for France and Italy, 15 for Norway; and the checksum from ISO 13616 must hold: move the first four characters to the end, turn each letter into a number (A is 10, Z is 35), and the resulting number, divided by 97, must leave exactly 1. That last test catches every single mistyped character and nearly every pair of swapped neighbours.

A valid IBAN is not an open account. The page checks the format only; it asks no bank anything and cannot know whether the account exists, who holds it, or whether it can receive money. Nor does it check the national rules inside the account part — some countries add their own check digits there. When the checksum fails, the page names the check digits that would fit the account part as typed, but a mistyped account digit is far likelier than wrong check digits, so compare the whole number against the source rather than just changing those two.

Lengths come from the SWIFT IBAN registry. A country the page does not list has its checksum checked and its length left unchecked, and the page says so rather than guessing. Spaces, dashes and lower case are accepted and ignored. A list is checked line by line, up to 1,000 lines. Nothing you paste is sent or stored; the Dark button keeps its own setting in this browser's local storage.