Validate a B2C Cardholder

Checks a B2C cardholder's personal data against the rules POST /v1/users/{id}/cardholder applies, without storing anything or sending anything to the card provider. Call it when your customer submits the form, so they can correct a field at once instead of waiting for a refused cardholder.

The body takes the user meta fields of a B2C cardholder (see POST /v1/users/{id}/cardholder) and the ssn. The values are normalized first, as on create: the post code loses its spaces, the address is transliterated to English letters, the nationality is upper-cased, a phone code without + is accepted. The country and town are checked against the live lists (/v1/cardholders/regions, /v1/cardholders/cities); when those cannot be read, that check is skipped, townChecked is false, and valid can still be true although the create, which needs the lists, would then refuse.

The answer is always 200 for a readable body: valid says whether the values pass the create's checks, and problems lists each refused field with the reason, one entry per field.

It checks the values only, not the user they are meant for: the body names no user. So valid: true does not promise the create succeeds. The create still refuses when the user's KYC is not completed, or when the email is already held by another cardholder on that card type. It also works on a cardholder the user already has on that card type (returns it, or submits it again) instead of creating one, and then asks for no SSN when one is on file, where this always asks a U.S. national for one.