The Klarna-api-bundle PHP SDK by asgoodasnu is an SDK that integrates and wraps the Klarna API into a symfony2 bundle. The Klarna API allows developers to integrate Klarna's functionality with other applications. Some example API methods include emailing invoices, crediting invoices, calculating costs, and managing inventories.
Hong Kong's government monetary authority recently released an Open API framework. Further, the government entity announced that it will launch an Open API next week. The framework includes a four phased approach that it expects Hong Kong banks to adopt in compliance with a roadmap.