The Recurly Ruby Sample Code by Recurly demonstrates how to use the API token to implement billing features into applications. In particular, this project uses Sinatra framework with the aim to redirect the APIs to different routes. Available at http://www.sinatrarb.com/
SumUp, a mobile payments rising star, recently announced an API that allows third party apps to accept credit card and cash payments without leaving the app. Prior to the API, SumUp users and customers were required to use the SumUp app in isolation from the merchant app to utilize the slick mobile payments platform.
Dwolla has launched a number of services and APIs in the recent past in an attempt to achieve its goal of "building the ideal API to move money." In an attempt to streamline its various services, Dwolla has repositioned its Access API to act as the umbrella to house all of its payment services.