Generates card numbers that pass Luhn and brand checks for testing checkout forms and validators: real issuer prefixes for Visa, Mastercard, American Express, Discover, Diners Club, JCB, UnionPay, Maestro and Mir with correct lengths, digits from the browser's cryptographic random source, and optional future expiry dates, CVV lengths per brand and sample cardholder names. The numbers belong to no account and are declined by real processors — use your payment provider's published test cards for end-to-end payment tests. Everything runs locally.
expiry adds MM/YY and CVV; full also adds a sample cardholder name.