As we discovered in Part 1 there is a set pattern to credit card numbers as well special identifiers for each card type (i.e. Visa cards start with a four). Knowing this allows us to validate a credit card number before we send it to the payment gateway to be sent to the processing bank [...]
After blogging about verifying credit card numbers it became apparent that some web developers may think if a credit card passes validation that it is a legitimate credit card. This is not the case. The validation presented in that blog entry as well in tomorrow’s entry only verify that a credit card number is in [...]
Performing address verification (AVS) is a must for any non-retail business, especially Internet-based merchants. Popular gateways like Authorize.net make performing AVS easy. You only need to send over the customer’s zip code and full street address to perform AVS successfully. However, other less popular and advanced gateway like the LinkPoint API require you to provide [...]
Any good web developer will tell you that you must always validate user input before doing anything with it in your software. The primary reason for this is to prevent malicious users from entering bad data that can harm your website. But another reason for this is honest users may erroneously enter invalid data. This [...]
Looks like Google has already signed up a bunch of merchants to their new checkout system Google Checkout. They are now even offering $10 and $20 off for various stores using their new system. This includes shopping at StarBucks and CD Universe. Now you can check out Google’s new payment system and save yourself some [...]
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