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
Free IBAN validator
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
- Local format and checksum checks
- 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?
The checker uses a built-in country-length table. A country absent from that table is reported as unsupported. It does not query the current IBAN registry or a bank directory.
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.
IBAN validation is not account verification
This checker answers a narrow question: does the value have the expected structure, a supported country length and a valid MOD-97 checksum? A passing result does not establish that the account exists, belongs to a named person, accepts payments or is safe to pay.
The format and checksum are checked locally. Requesting the signed AffixIO result makes a network call with the check outcomes and country code; the tool does not send the full IBAN in that request. A signature records the evaluated outcome, not a bank's confirmation.
Try these format examples
These are published-style validation examples for testing the checker. Do not send money to them.
| Country | Example IBAN | Length |
|---|---|---|
| Germany | DE89 3704 0044 0532 0130 00 | 22 |
| United Kingdom | GB29 NWBK 6016 1331 9268 19 | 22 |
| Netherlands | NL91 ABNA 0417 1643 00 | 18 |
Why can a check fail?
Common causes include missing characters, a mistyped check digit, punctuation, a country-length mismatch or a country absent from this tool's reference table. Spaces and letter case are normalised. An unsupported country is not evidence that a real bank account is invalid.
SWIFT maintains the official IBAN registry. Consult that registry for current country formats; this tool does not perform a live bank-directory lookup.
Record the result in your own application
For a wider verification workflow, connect your authorised data source, evaluate a defined condition and retain signed evidence with the AffixIO SDK. See the other public tools for demonstrations with different data scopes.