Too bad their developer site will most likely spend more time convincing me about their "solutions" than showing me what it means in code. If MasterCard wants

Too bad their developer site will most likely spend more time convincing me about their "solutions" than showing me what it means in code. If MasterCard wants me to commit to their platform, give me a Rails plugin (and SDK/plugins for other popular platforms/languages) and show me sample code. Show me how simple it is. I think this is generally applicable to a lot of APIs offered by established companies. In terms of payment APIs active_merchant is the gold standard: http://www.activemerchant.org/ http://www.activemerchant.org/. It took me about 20 seconds to be fully convinced that it was what I wanted to use.