Although Estimote have recently implemented a cloud-based platform, their beacons can quite happily work independent of it, and their beacons conform to the iBeacon specification as set out by Apple.
On top of the features laid out by the iBeacon specifications, Estimote beacons also include a temperature sensor and accelerometer for additional functionality.
Currently, the only data that is actually synchronized to the cloud is a property representing the color of the silicon case that surrounds the beacon and a single property signifying the beacon's location. This property is just intended as a reference for you as the beacon owner. When you purchase beacons from Estimote, they automatically add your beacons to the cloud platform.
