How the IBAN Validator Works

What the Tool Does

This IBAN validator checks International Bank Account Numbers for correct structure, country length, and checksum using the Mod-97 algorithm. It normalizes the IBAN, formats it with spaces every four characters, and extracts key parts like country code, check digits, and BBAN.

Common Developer Use Cases

Developers use an IBAN checker to validate payment forms, verify bank account details in fintech applications, and debug integration issues with SEPA or international bank transfers. It is also useful when importing customer data or building validation rules for onboarding flows.

Format, Length, and Checksum

An IBAN starts with a two-letter country code followed by two check digits and the BBAN. Each country has a fixed IBAN length. This tool detects the expected length and validates the checksum, helping you spot common errors like missing characters, wrong country codes, or invalid check digits.

Common Pitfalls and Edge Cases

Spaces and casing do not affect validation, but hidden characters or copy/paste artifacts often do. Always normalize input and ensure the IBAN length matches the country rule. A checksum mismatch usually indicates a typo or a truncated value.

When to Use This Tool vs Code

Use this IBAN validator for quick checks and debugging. For production systems, validate IBANs server-side and store the normalized format. Consider additional business rules like bank availability or country restrictions in your application logic.