This document discusses interoperability and APIs in OpenStack. It provides an overview of OpenStack and discusses how standardized APIs like CDMI and OCCI are being developed and implemented for OpenStack to improve interoperability between cloud software stacks and address concerns of customers, politicians, and regulators regarding proprietary implementations and potential for lock-in. Examples are given of how CDMI and OCCI have been implemented to provide standardized interfaces for object storage and infrastructure management in OpenStack.