Do I need an API key?
No. The validation runs entirely in your browser. The signed verdict uses a throwaway demo key that the page requests from the live AffixIO API on its own.
Public tool
Is this bank account number valid?
Type any IBAN. IBAN Validator checks the country format and runs the MOD-97-10 checksum that every valid bank account number must satisfy, entirely in your browser, then asks the live AffixIO API for a signed yes or no.
- No API key
- No network call, runs in your browser
- Signed with ML-DSA-65
IBAN to validate
Type or paste any IBAN. Spaces are ignored. The check is instant and runs entirely in your browser.
AffixIO proof
- Proof
- Answer
- Audit
- Policy
- Signed
- Algorithm
- Digest
- Signature
Stamped by the live AffixIO API and signed with ML-DSA-65, the FIPS 204 post-quantum algorithm. Nothing personal goes into the payload.
How to use it
Three moves, no sign-up.
Type an IBAN
Paste or type any International Bank Account Number. Spaces are ignored.
Press Validate
The tool checks the country format and runs the MOD-97-10 checksum that every valid IBAN must satisfy. It runs entirely in your browser.
Read the verdict
A YES means the format and checksum both pass. A NO tells you which check failed, with a signed proof from the live AffixIO API.
What you are looking at
An IBAN is an International Bank Account Number. Every country has a fixed format: a two-letter country code, two check digits, and a country-specific length for the rest of the number.
The MOD-97-10 checksum is the international standard. The number is rearranged, letters are converted to digits, and the remainder when divided by 97 must equal one. Every valid IBAN in the world satisfies this.
The proof card shows the answer stamped by the live AffixIO API: a proof id, an audit id, the policy version, and an ML-DSA-65 signature over the payload digest.
Questions
Does this check the bank or account exists?
No. It checks that the number is correctly formed and has a valid checksum. It does not contact any bank.
Which countries are supported?
Every country that uses the IBAN standard, with country-specific length checks for each one.
What does the proof card show?
The answer stamped by the live AffixIO API: a proof id, an audit id, the policy version, and an ML-DSA-65 signature over the payload digest.