Distilling a rich and complex shopping site down into a native app on a small screen presents numerous challenges for UX and technology. Without an API to build upon, complex business rules had to be reverse engineered from Java source code in order to establish a Spring-based REST API to provide web services for the iPhone application. The iOS app translated many of the core features from the website to enable users to create new orders, add to existing orders, re-order items and schedule deliveries while maintaining a high degree of order customization that FreshDirect cutomers demand.