Omnipay is a PHP processing library that supports 26 reputable payment gateways, including PayPal and Stripe. This article shows you Omnipay's capabilities by verifying a customer's credit card information and then uses the SDK for making a payment through a Stripe payment gateway.
Square is moving beyond the retail terminal thanks to a handful of new APIs meant to help companies accept payments in more places. The E-Commerce API and Register API target retailers large and small with a simple set of tools that integrate fully with Square's payment processing platform.
Facebook added a new feature to its Facebook Credits API that allows developers to download reports regarding payments in their Facebook applications. The payment reports are generated daily by Facebook. Up until now, developers had been receiving payment reports via email.