IBAN validator
Check whether an IBAN is well formed before you send money its way: the check digit (ISO 13616, modulo 97), the national format and the length are all verified, and the number is re-grouped for reading. A transposed digit or a wrong country code is the usual cause of a bounced transfer, and this is the cheapest check there is. The IBAN is a public payment reference, but it still stays on your device — nothing is sent to a server.
- 100% local
- Free · no account
- Instant result
This tool runs entirely in your browser — nothing is sent to a server.
An IBAN (International Bank Account Number) uniquely identifies a bank account. It starts with a country code (BE, FR, LU…), followed by a two-digit check digit and then the national account number. A Belgian IBAN has 16 characters, a French one 27.
This validator checks the check digit according to ISO 13616 (modulo 97 computation) as well as the length for each country. It immediately catches a typo — before a transfer goes to the wrong account.
How it works
Type the figures or drop the file you want to process — the tool checks them as you go.
Everything is computed directly in your browser. Nothing is sent to a server.
The result appears instantly, with the detailed breakdown ready to copy, download or keep.
Why use this tool
No account, no download, no limit: the result appears as soon as you enter your data.
Every rule, algorithm and check reflects what we use ourselves every day at Flexina.
The calculations follow the official standards, and the step-by-step detail lets you double-check the outcome.
What does running it locally bring you?
Files, figures and documents never leave your device: nothing is stored, nothing is sent.
Once the page is loaded, you can cut the network: the tool keeps working.
No upload, no account, no third-party server in between: results stay fast and fully private.
Frequently asked questions
Does a valid IBAN guarantee the account exists?
No. Validation confirms the format and check digit are correct, i.e. it is a plausible IBAN. Only your bank can confirm the account is actually open.
How is the check digit calculated?
The first four characters are moved to the end, the letters are converted to digits (A=10 … Z=35), and the resulting number must give a remainder of 1 when divided by 97.
Are my account numbers sent anywhere?
No: the check runs entirely in your browser, no data leaves your device.