The Spreedly Python SDK by Dani allows API communication to integrate payment features into web services. Resources include installation and documentation. Spreedly interacts with Authorize.net, WorldPay, and CyberSource as payment gateways.
The Currency Cloud, cross border payment as a service provider, has enabled developers to integrate international payment processing with an API: XBPConnect. Prior to the Currency Cloud, payment/invoice software required users to leave the platform and engage a third party to process an international invoice. The Currency Cloud allows cross border and multi-currency transactions from a single platform. The API allows developers to integrate the functionality into existing apps and platforms.
Without the dot, "cardio" is Rule #1 in Zombieland. With the dot, card.io is PayPal's latest acquisition: the startup formerly known as Lumber Labs, whose technology allows developers to integrate credit card payments into any iOS or Android app with no additional hardware.