IBAN Validator

This tool checks whether an International Bank Account Number (IBAN) is structurally valid. It strips spaces, parses the country code and check digits, verifies the total length against the country-specific expected length for 80+ countries, and runs the official ISO 13616 modulo-97 checksum using BigInt to confirm the IBAN is internally consistent.

1. Type or paste the IBAN into the input; spaces are allowed and will be stripped automatically. 2. The result card appears as you type, showing the parsed Country code, Check Digits, and BBAN. 3. Read the validity banner: green for a valid IBAN, red with a specific reason for an invalid one. 4. Use the parsed fields to confirm each segment before using the IBAN for a transfer.

Validation runs in order and reports the first failure: 'too short' if fewer than 4 characters; 'invalid country' if the first two characters are not letters; 'invalid check digits' if positions 3-4 are not numeric; 'unknown country' if the country code is not in the supported table; a length mismatch if the total character count differs from the country's expected length (for example 22 for GB, 27 for France, 22 for Germany); and finally 'checksum failed' if the modulo-97 remainder is not 1. The checksum moves the first four characters to the end, converts letters A-Z to 10-35, and takes the whole numeric string mod 97.