Management of large application state is one of the hardest problems for cloud and edge apps today. We demonstrate FASTER, a new open-source concurrent key-value store from Microsoft Research, that supports larger-than-memory data while providing unprecedented performance for the hot working set in main memory. FASTER achieves up to orders-of-magnitude better throughput than systems deployed widely today. FASTER is available in C# and C++ and can work with any storage backend such as local SSD and cloud storage. FASTER is currently being integrated into services such as Azure Stream Analytics. Our demonstration focuses on: (1) the ease with which cloud applications and state stores can deeply integrate state management into their C# or C++ logic at low overhead; and (2) the innovative system design and the resulting high performance, adaptability to varying memory capacities, durability, and natural caching properties of our system.