The Mobile Cloud Services offering of IBM Bluemix® is a platform for cloud-based mobile applications, providing data and file storage, application authentication, push notifications, and server-side application logic, all available through easy-to-use client software development kits (SDKs). In this paper, we describe the server-side architecture for the key components of the Mobile Cloud Services. For scalability and fault resilience, components are implemented as stateless services that communicate using a distributed message queue. We adopted a “design for failure” approach to all environmental services, including basic networking support. We developed a robust communications layer that adds timeout and retry logic to all external interactions. We also built a flexible and robust application-monitoring infrastructure to constantly probe the service components, test end-to-end functionality, and report any problems through web monitors and text messages. Finally, we designed and delivered client SDKs for Android®, iOS®, and JavaScript® that enable application developers to quickly create robust mobile applications that utilize IBM Mobile Cloud Services. These architecture and implementation choices have resulted in a robust and scalable cloud-based platform for mobile application developers.