One of the things I have to do on a regular basis is run a suite of regression tests against Copilot’s payment system to ensure that we’re doing basic vetting of invalid credit cards, such as those that do not have valid Luhn checksums. To that end, I was very happy to discover a list of credit card numbers that I could use for testing purposes. The numbers aren’t for valid cards, but should pass any basic validation check you have in a commerce site you write.