SportNinja currently supports Apple and Android devices as well as Web Browsers (for Admin use).
We recommend devices that are less than 3-5 years old, as older devices start to experience performance degradations.
Amazon Fire HD is not an Android device and runs on an operating system called Fire OS. There are ways that users can try to install applications and services on the Fire HD using workarounds, but Fire HD is not formally supported by the Google Play store.