[alberth2]

Free plans by using a test credit card # (e.g. 4111111111111111).

It works.

Good job 37signals. You instill so much confidence in your in attention to details in your product. Much like the recent known Rails security vulnerability that you never addressed and now Github was compromised as a result.

[joevandyk]

I don't see a problem with accepting a test credit card. Once your free trial is over, then they'll email you a message saying your card can't be charged and you'll be expected to update it.

[alberth2]

No, this is a major bug because they are trying to authenticate the credit card before accepting the input in the form field. Meaning, if you type "1234567891234567" that won't work, yet a test credit card # does work.

[m0nastic]

This isn't a bug.

The validation that they are doing when you enter the card is just Luhn validation.§

This is basically just to ensure that the numbers entered into the field "at least have the possibility of being a valid credit card". No processing of the card is being done at this stage.

§ - http://en.wikipedia.org/wiki/Luhn_algorithm

[joevandyk]

They aren't authenticating the card. They are doing a checksum on the digits entered using the luhn algorithm.

[functionform]

Exactly, its not a bug, its a feature. Just like mass assignment.