IBAN Validator

Audience: Low-code Engineers

Skill Prerequisites: Forms

The IBAN Validator add-on checks that a value is a valid International Bank Account Number (IBAN). It adds an IBAN validator that you attach to a form field, for example a text box where users enter their bank account. If the IBAN isn't valid, the form isn't submitted and the user sees a message that says what's wrong.

note

This add-on is the PlantAnApp.IbanValidator package, with product code IBANVLD. It's installed separately. The validator doesn't check the license when it runs. If IBAN isn't in the list of validators, the add-on isn't installed.

What it checks

The validator uses the IbanNet library and checks the whole IBAN against the rules for its country:

• Characters. The IBAN can't contain symbols such as - or /, and the first two characters must be letters.
• Country. The country code must be a country that uses IBANs.
• Length. The IBAN must have the length set for that country.
• Structure. The account part must follow that country's pattern of letters and digits.
• Check digits. The two check digits after the country code must match the rest of the number.

It doesn't check that the account exists or that it's open. For that, you need your bank or a payment provider.

Adding it to a field

In Forms, open the field's Validation section and pick IBAN in Custom Validator #1 or Custom Validator #2. See Validation.

In Forms 2.0, open the field's Validation panel, click Add Validation and pick IBAN. See Field Validators.

The validator has no settings. To make the field mandatory, also turn on Required, or add the Required Field validator in Forms 2.0. In Forms, an empty field isn't checked by the IBAN validator.

Error messages

The check runs on the server when the form is submitted. The browser doesn't check the value while the user types. When the IBAN isn't valid, the user sees one of these messages:

Problem	Message
Symbols or other characters that aren't allowed	The IBAN contains illegal characters.
The first two characters aren't letters	The IBAN contains illegal characters in the position where the country code is expected.
Unknown country code	The country code is unknown/not supported.
Wrong length for the country	The IBAN has an incorrect length.
Wrong pattern for the country	The pattern of the IBAN is incorrect.
Wrong check digits	The IBAN check digits are incorrect.
Any other error	An error was encountered while validating the IBAN.

The messages come from the add-on. In Forms 2.0, a custom Message on the validator isn't used. They're stored in DesktopModules/DnnSharp/Common/App_LocalResources/IbanValidator.resx, with a Romanian translation in IbanValidator.ro-ro.resx. To change or translate them, edit these files or add a file for your language. Your changes can be overwritten when the add-on is upgraded.

Considerations

• Save it the way you need it. The validator doesn't change the value. If you need the IBAN in a fixed format, for example without spaces and in capitals, clean it up in your actions before you save it.
• Only Forms. The validator works on form fields. It isn't an action, so it can't check IBANs in workflows or API endpoints.

Revised 10/02/2026