Our mobile apps are using an increasing number of AI models, some of which can be quite big. Sometimes these models will be in the cloud. Some other times, we need the models on the device, and we need to deliver the right model to the right users minimising the storage space we use on their devices and costs. We'll discuss the pros and cons of the alternatives we've considered and what choices we've made for different features in the Microsoft SwiftKey AI Keyboard app.