IBAN Validator & Parser

How to use

1. Paste an IBAN into the input. Spaces, hyphens, and case do not matter — the tool normalises them automatically.
2. Validation runs as you type. The Status card shows whether the IBAN is valid, the country, the check digits, and the expected length.
3. The BBAN Components card breaks the country-specific part into Bank Code, Branch Code, Account Number, and any national check digit defined by the SWIFT IBAN Registry.
4. The Formats card lets you copy the IBAN in print format (groups of four), machine format (no spaces), or just the BBAN portion.
5. Use Load Example to drop in a published sample IBAN for a country you want to test against.

What an IBAN actually is

IBAN (International Bank Account Number) is defined by ISO 13616 and maintained by SWIFT. It packs four things into a single string: a 2-letter ISO country code, a 2-digit checksum, and a country-specific BBAN (Basic Bank Account Number) that holds the bank, branch, and account identifiers in a fixed layout. Length is fixed per country — 15 characters for Norway, 22 for the UK, 34 for Saint Lucia — and every position has a defined character class: digits, letters, or alphanumeric.

How the mod-97 check works

The checksum algorithm is deliberately simple and runs in the browser in microseconds:

1. Remove spaces and uppercase the IBAN.
2. Move the first 4 characters (country + check digits) to the end.
3. Replace every letter with two digits: A → 10, B → 11, … Z → 35.
4. Treat the resulting digit string as a single integer and compute n mod 97.
5. If the remainder is 1, the checksum is correct.

Letters can appear in the BBAN of many countries (UK bank code, Germany has none, Italy starts with a letter check), which is why mapping letters to digits is a core step rather than an edge case. ZeroTool uses native BigInt when available and falls back to a chunked modulo on older browsers.

What the BBAN breakdown shows

• Bank Code — identifies the issuing bank within the country. May be letters (UK, Netherlands, Ireland), digits (Germany, France, Italy), or alphanumeric (Switzerland, Albania).
• Branch Code — many countries carve out a sub-identifier inside the BBAN for the branch/sort code (UK sort code, French code guichet, Spanish oficina).
• Account Number — the bank-internal account identifier.
• National Check Digit — countries like France, Italy, Belgium, and Hungary embed an extra national check inside the BBAN, in addition to the IBAN mod-97. It is shown for completeness; this tool does not separately verify national check algorithms.
• Account Type / Holder Indicator / Currency Code — country-specific fields (Brazil includes account type + holder; Mauritius and Seychelles include a currency code; Bulgaria includes an account type code).

Typical use cases

• Catching transposition typos before submitting a SEPA transfer or wire instruction.
• Sanitising user-submitted IBANs in checkout forms — a client-side mod-97 check is the cheapest first filter before a paid validation API.
• Inspecting test IBANs from payment gateways (Stripe, Adyen, Mollie, Braintree) to verify which country layout they follow.
• Debugging OCR results from invoices: the most common OCR errors (0/O, 1/I, 5/S) all break mod-97, so the tool flags them instantly.
• Confirming the bank code matches the bank you expected before paying an unfamiliar invoice.

Limits by design

This tool is a validator and parser, not a bank-account lookup service. It does not call any external API and cannot tell you whether an account is open, frozen, or owned by a particular person. It does not generate IBANs from raw bank codes — that capability has obvious abuse potential and is intentionally absent. For BIC/SWIFT codes, use the official SWIFT directory or your bank’s online resources. For SEPA payment QR codes, use the QR Code Generator tool on ZeroTool with an EPC069-12 payload.