IBAN Validator — Official mod-97 Check, Locally

How to use

1. Paste the IBAN (spaces are ignored).
2. Press Validate.
3. Read verdict + parsed parts.

General information only — not medical, financial or legal advice. Figures cross-checked against public official sources (IRS / HMRC / NHS / WHO guidance); content last reviewed September 2026. For decisions that matter, confirm with a licensed professional in your country.

About this tool

A single mistyped digit in an IBAN can bounce an international payment. This validator implements the official ISO 13616 check: country-specific length table, character set rules, and the mod-97 checksum (remainder must equal 1). It also shows the parsed country code and bank identifier so you can sanity-check the origin. Everything runs locally — bank details are sensitive, and they never leave this page. Your file never leaves this page — everything runs in your browser, there is no upload endpoint on this site, and the file is dropped from memory when you close the tab.

How the mod-97 Check Catches Typos (2026 Guide)

Every IBAN hides a checksum that makes 97 divide cleanly through the number — and this validator runs that exact ISO 13616 check in your browser: shape, country length table, character set, then the mod-97 arithmetic. Below is the anatomy of a real IBAN, worked examples with the actual remainders, and the boundary between "valid" and "will actually arrive".

Anatomy of a valid IBAN

Take the standard-format example GB82 WEST 123456 98765432 (22 characters, as every UK IBAN must be):

Worked checks you can run above

The third row is the entire point: a one-character change anywhere in the number rearranges the mod-97 remainder (here to 39), and the validator says so in plain words instead of a bounced transfer three business days later. The check catches every single-character substitution and most adjacent transpositions — roughly the totality of human typing errors.

Valid is not the same as money arrived

A green check means the string is structurally perfect for its country: right length, right characters, right checksum. It does not mean the account exists, is open, accepts your currency, or that the beneficiary name matches — banks reject on all four for structurally valid IBANs. Use validation as the first gate, then confirm the payee out-of-band for first-time transfers. Pair it with the currency converter to sanity-check the amount crossing borders, and the invoice generator to put correct payment details on what you send clients.

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