The Internet of Things (IoT) holds the promise of a new wave of app development: IoT apps. It interweaves sensors, connected devices, networking, cloud, and analytics—elements that can be combined in countless ways to yield new applications. The rub is the complexity. Toolsets from platforms like the recently launched Brillo from Google and HomeKit from Apple help to cope with the maze that is the IoT. Smart developers will pay particular attention to the integration of the ecologies and sub-systems across the universe of the IoT.