The cards generated will pass the valid credit card formula but will not pass charging through credit card processors. Beyond creating credit cards this is a list of cards we often will use that many credit card processors know are fake credit cards and will pass their tests in their developer sandboxes.
Credit Card Prefix Numbers
AMEX: 15 numbers starting with 34 or 37
Diners: 15 numbers starting with 300, 301, 302, 303, 36 or 38
Discover: 16 numbers starting with 6011
Enroute: 16 numbers starting with 2014 or 2149
JCB 15: 16 numbers starting with 2100 or 1800
JCB 16: 16 numbers starting with 3088, 3096, 3112, 3158, 3337 or 3528
MasterCard: 16 numbers starting with 51, 52, 53, 54 or 55
Visa: 13 or 16 numbers starting with 4539, 4556, 4916, 4532, 4929, 40240071, 4485, 4716 or 4
Voyager: 13 or 16 numbers starting with 8699