PayPal has officially released PayPal X, its next generation platform that includes a variety of APIs and other resources for developers. Primarily aimed at allowing developers to embed payment processing in a wider array of applications and environments, this is a major expansion of PayPal's APIs.
Payleven, the Square equivalent for the world outside of the US, has launched an API to complement its mobile payment device. Prior to the API, use of Payleven's mobile payment device required downloading the Payleven app (similar to Square's current model). However, the API allows developers to integrate Payleven's functionality within third party apps.