AMERICAN EXPRESS: 3111-1111-1111-1117
VISA - 4111-1111-1111-1111
MASTERCARD - 5111-1111-1111-1118
DISCOVER - 6111-1111-1111-1116
2. How to test over limit on a credit card?
Use a prepaid VISA gift card. Pick one for 25$, go over the limit, see what happens when the card is declined. This is great as there is no revealing of personal card information in the wild