IBAN Validator
Check IBAN structure, country length and MOD-97 checksum. Review reported national-check coverage and learn why a valid format does not verify an account.
A checksum is one layer of validation.
IBAN validation combines country structure, length, BBAN pattern and the international MOD-97 checksum. Available national or bank-specific rules add another layer. Use the detailed result to understand which checks were performed and which remain outside the tool’s coverage.
- 01
Start with a known fixture
Use a published format example or a generated synthetic sample. Keep its intended country and expected result beside the test.
- 02
Read failures and coverage separately
A failed implemented check differs from an unavailable national rule. Preserve that distinction in your application’s error message.
- 03
Test normalization and mutation
Compare spaced display input with the normalized value. Then change a check digit or remove a character to create an explicit negative case.
Example: same identifier, different display
Display: DE89 3704 0044 0532 0130 00
Stored: DE89370400440532013000
Mutation: DE88370400440532013000The first value is a published format example. The last changes a check digit. Use it to compare normalization and checksum behavior, never as a payment instruction.
| Outcome | Interpretation | Next test |
|---|---|---|
| Checksum passes | International mathematics is consistent | Inspect other checks |
| National coverage missing | Some rules were not evaluated | Retain the coverage message |
| Length fails | Structure differs from the country rule | Check the complete input |
Before you use the result
Practical answers for your next test.
Does incomplete mean invalid?
Not necessarily. It can mean required reference data or a national rule was unavailable. Inspect the actual failures and coverage details.
Should I remove spaces before storing?
Use a consistent normalized text representation and add display spaces separately. Never store the identifier as a number.
Can this confirm ownership?
No. Account ownership requires a separate process with the relevant financial service.