Verify the mathematical validity of any International Bank Account Number (IBAN)
System Definition BlockVerify IBAN numbers instantly using the MOD-97 checksum algorithm. Support for over 70 countries to ensure accurate international wire transfers.
WebToolkit Pro is engineered for zero-trust environments. This utility processes your sensitive data entirely within your browser using Web Workers.
The engine executes the official Modulo-97 algorithm locally in your browser. First, it moves the first four characters (the country code and checksum) to the end of the string. Next, it converts all letters into numbers (where A=10, B=11, up to Z=35). Finally, it treats this massive string as a giant integer and divides it by 97. If the remainder is exactly `1`, the IBAN is mathematically valid. It also cross-references the length against specific national registry standards.
function isValidIBAN(iban) {
const clean = iban.replace(/\s/g, '').toUpperCase();
const rearranged = clean.slice(4) + clean.slice(0, 4);
const numericStr = rearranged.replace(/[A-Z]/g, match => match.charCodeAt(0) - 55);
// Use BigInt because the numeric string exceeds JavaScript's MAX_SAFE_INTEGER
return BigInt(numericStr) % 97n === 1n;
}No. This tool only validates the mathematical structure of the number, ensuring it is impossible for it to be a typo. It does not ping SWIFT networks or query the actual bank to see if the account currently has money or is actively open.
No. The length of an IBAN varies strictly by country. A German IBAN is exactly 22 characters long, a French IBAN is 27 characters, while a Maltese IBAN is 31 characters. The algorithm verifies your input against these specific national standards.
Yes. An IBAN alone cannot be used to withdraw money from your account; it is strictly routing information for depositing funds. Furthermore, our tool executes 100% client-side in your browser, meaning the number is never transmitted to our servers.
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Explore All WebToolkit Pro ToolsZero-Knowledge Protocol: To guarantee absolute user privacy, this tool executes 100% client-side inside your web browser via WebAssembly and local JavaScript. None of your input strings, payloads, keys, or files are ever transmitted to a remote server.
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