Question 1

Is this tool really offline?

Accepted Answer

Yes. Once loaded, the page makes no further network requests — every check runs in your browser. Save it with Ctrl+S and it keeps working with no internet at all.

Question 2

Is my IBAN sent or stored anywhere?

Accepted Answer

No. What you type never leaves your device. The server only delivers this static page and technically cannot see, log or store your input. No cookies, no analytics.

Question 3

How is the checksum calculated?

Accepted Answer

With the international MOD-97-10 method (ISO 7064): letters become numbers, the IBAN is rearranged, and the remainder after division by 97 must equal 1.

Question 4

Why is a valid IBAN no proof that the account exists?

Accepted Answer

Validity only means the number is formally correct. Whether the account is open and belongs to the intended recipient can only be confirmed by the bank.

Question 5

Why doesn't the bank name appear?

Accepted Answer

Names and BICs come from open registries (~22,500 bank codes across 37 European countries). New or exotic codes may be missing — that changes nothing about the validity result, but double-check the IBAN.

Question 6

Can I validate non-European IBANs?

Accepted Answer

Yes. Format and checksum are verified for all ~127 IBAN countries; bank identification and SEPA details are available for Europe.

Question 7

What does the * placeholder do?

Accepted Answer

Replace up to four uncertain characters with * and the tool computes which combination yields a valid checksum — locally, of course.

Question 8

Under what license can I use this page?

Accepted Answer

Free for personal use — save it, keep it, use it offline as much as you like. The page itself is licensed under CC BY-NC-ND 4.0: you may mirror and share it unchanged for non-commercial purposes with a link to the original. Commercial reuse needs permission (see the legal notice).

Question 9

I have a feature request or found a bug — where do I report it?

Accepted Answer

Ideas travel best attached to a coffee on the support page — caffeine demonstrably speeds up development. ;) Bugs can of course also be reported for free via the contact address in the legal notice.