IBAN validator
Check any international bank account number — checksum, length, country and SEPA membership. Spaces are ignored. Nothing is looked up at a bank, so this tells you the number is well formed, not that the account exists. No signup.
One at a time is the demo. A list is the job.
Checking one value tells you about that value. The reason anyone does this at all is the other few thousand — last week’s signup export, the list you inherited, the file nobody has opened since. Paste or upload it and every row is scored: emails, phone numbers, IPs and domains mixed together, duplicates removed and counted first.
Check a whole list — free, no signup →Same check from your code
IBAN validation needs no data from us, so it is not an API endpoint — it is arithmetic you can run yourself. What the API does check on a payout form is everything that arrived alongside it: the email, the phone number, the IP and the domain.
curl "https://www.layercall.com/v1/score/user?email=payee@example.com&ip=8.8.8.8" \ -H "X-Api-Key: YOUR_API_KEY"
1,000 lookups a month free, no card. Get a key or read the docs.
What each signal means
Checksum
The ISO 13616 mod-97 remainder over the whole string, which must come out at 1.
This is what makes an IBAN self-proving. Change one character or swap two around and the remainder stops being 1, so the overwhelming majority of typos are caught before a payment is ever attempted.
Length
Every country has one fixed IBAN length — 22 for the UK, 27 for France, 31 for Malta.
Checked before the checksum because it gives a better answer. 'A GB IBAN is 22 characters, this is 21' tells someone what to look for; 'checksum failed' does not.
Country
The first two letters, matched against the SWIFT IBAN registry.
A country that does not issue IBANs at all is a different mistake from a mistyped one — usually a US account number pasted into an IBAN field, since the US has no IBAN scheme.
SEPA
Whether the country is in the Single Euro Payments Area.
A SEPA transfer is same-day, low-cost and reversible on a known timetable. Outside SEPA the money moves slower and comes back harder, which changes how much you want to trust a new payee.
Questions
Does a valid IBAN mean the account exists?
No, and this is the thing worth being clear about. Validation is arithmetic on the string — it proves the number is correctly formed, not that anyone holds it. Only the receiving bank knows whether the account is open, and no API that takes a string alone can tell you otherwise.
Is my IBAN sent anywhere?
The number is sent to compute the answer and is not stored. Nothing is looked up at a bank, and there is no record of the accounts you check.
Why is IBAN not part of the API?
Because it needs no data we hold. The checksum is a dozen lines of arithmetic you can run in your own code with no network call and no key — putting it behind an API would be charging for a mod-97. The API covers what genuinely needs looking up: email, phone, IP and domain reputation.
Which countries are supported?
Every country in the SWIFT IBAN registry — around 90, covering all of SEPA plus much of the Middle East, North Africa and the Caribbean. Countries with no IBAN scheme, the US and Canada among them, are reported as such rather than failed as a typo.