IBAN Checker: Validate IBAN Numbers and MOD-97 Checksum
An IBAN checker validates an International Bank Account Number against the length and structure rules for its country and the ISO 7064 MOD-97-10 checksum, then breaks the number into its country, check-digit, bank, branch, and account parts.
Validate an IBAN and break it into country, check digit, bank code, branch code, and account parts.
Check an IBAN
Enter a value and run the check. Everything runs locally in this page.
Run up to 10,000 validations/mo at <5ms edge latency with zero data retention and 99.9% availability.
curl -X POST https://api.stanzaapi.com/iban-validator/api/v1/iban/validate \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{"iban": "DE89370400440532013000"}'Runs entirely in your browser. The value you type is never sent to a server.
How to check an IBAN number
- Paste the IBAN — Enter the IBAN with or without spaces. The checker uppercases it and removes separators before validation.
- Run the MOD-97 checksum — The checker rotates the first four characters to the end, converts letters to numbers (A=10 to Z=35), and verifies that the remainder modulo 97 equals 1.
- Read the structure result — The result shows the country, expected and actual length, BBAN structure, bank code, branch code, and the print format.
What the check verifies
The check verifies three things: the ISO 7064 MOD-97-10 checksum, the country-specific IBAN length, and the national BBAN character pattern. A number can pass the checksum and still be invalid if its length or BBAN structure does not match the country rule.
The checker normalizes the value, computes the ISO 7064 MOD-97-10 checksum, and compares the number against the registered length and BBAN pattern for its country. When the structure is valid it also extracts the national bank and branch identifiers from their registered BBAN offsets.
IBAN validation is a format and checksum test, not a registry lookup. A number that passes can still belong to a closed account or contain a valid but unassigned bank code, so confirm payment details with the account holder.
IBAN length and structure by country
Frequently Asked Questions
The third and fourth characters of an IBAN are the check digits. They are computed with ISO 7064 MOD-97-10 so that the remainder of the rearranged number modulo 97 equals 1.
A bank-issued IBAN can fail if a character was mistyped, if hidden characters were copied with it, or if its length does not match the country rule. Compare the value with the source document and remove spaces or punctuation before checking again.
An IBAN is between 15 and 34 characters. The exact length is fixed per country: a Norwegian IBAN is 15 characters, a German IBAN is 22, and a Russian IBAN is 33.
No. The validation runs as JavaScript in your browser and the IBAN you type is not transmitted to Stanza or any third party.
The free checker validates one IBAN at a time. The Stanza IBAN Validator API accepts batch requests and returns the same checksum, structure, and bank-code fields for every number.
Free browser tool vs Stanza API
| Capability | Free browser tool | Stanza API |
|---|---|---|
| Where it runs | Your browser | Cloudflare edge |
| Authentication | None | Bearer API key |
| Rate limit | None | Published per-tier limits |
| Data handling | Never leaves your device | In-memory, zero retention |
| Batch validation and BIC/SWIFT validation through the IBAN Validator API | No | Yes |
| Typed JSON envelope with latency metadata for server-side integrations | No | Yes |