I've been working on a shopping cart solution the last couple of days and need to test Credit Card numbers that conform to the Luhn formula (MOD 10 check).
These are NOT valid credit card numbers. They are random numbers that happen to conform to the MOD 10 algorithm. You cannot use them for purchasing anything, you cannot use them for anything other than testing e-commerce sites (because they should get past any pre-validation you do, and be declined at the card processor or bank stage).
Mastercard
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5490498152740777
5593187659997503
5542262305368243
5551285794283472