IBAN Validator

Validate IBAN account numbers via the standard mod-97 checksum. Decode country, bank code, branch code, account number from a single paste. Catch typos before they cost a wire transfer fee. All validation runs locally — your IBAN never reaches a server.

What an IBAN encodes

International Bank Account Number — a single string identifying a bank account anywhere in the IBAN-using world. Format:

DE 89  3704 0044  0532 0130 00
│  │   │             │
│  │   bank code     account number
│  check digits
country code

The check digits make the whole string self-validating via mod-97 — a wrong character almost certainly fails the checksum.

What this tool does

1. Strip whitespace.
2. Validate length matches the country’s IBAN format (each country has a fixed length).
3. Compute mod-97 over the rearranged numeric form.
4. Decode country, bank code, branch code, account number using the country’s specific layout.

If valid, you get a clean breakdown. If invalid, the tool tells you why — checksum failed, length wrong, country not recognized.

Common workflows

Sanity-check before a wire transfer. Customer or coworker dictates an IBAN. Paste here. If invalid, ask for the correct number before initiating the transfer (and incurring the failed-wire fee).

Validate a payments form. Build server-side validation, but adding this tool to a docs page lets users debug their own input before submission.

Audit a stored set of IBANs. Run a list through to catch any that drifted (manual data entry, OCR errors).

Look up a bank. The bank code maps to a directory entry — your bank’s compliance team will use the country code + bank code to identify the institution.

Why local IBAN checking

IBANs are PII when paired with a name. Pasting them into a remote validation service exposes that pairing to whoever runs the site. Ours validates locally — paste freely, leave nothing behind.

Last updated: 2025-01-15