Fire OS

Fire OS is a Stock Android ROM made by Amazon for Fire Tablet's, Fire TV and Echo Smart Devices,

Fire OS is based on the Android Open Source Project, and does not contain any of Google's proprietary services. Instead, Amazon created substitutes for Google's proprietary services and API's, including a appstore, in-app purchasing, mapping, and push notification services, etc, none of the the Amazon substitutes are open source.

History
Fire OS 5, which is based on Android 5.0 "Lollipop", added an updated interface. The home screen now features a traditional application grid and pages for content types as opposed to the previous carousel interface. It also introduces "On Deck", a function which automatically moves content out of offline storage to maintain storage space for new content, the speed reading tool "Word Runner", and screen color filters. Parental controls were enhanced with a new web browser for FreeTime mode featuring a curated selection of content appropriate for children, as well as "Activity Center" for monitoring usage by children. Fire OS 5 removed support for device encryption; an Amazon spokesperson stated that encryption was an enterprise-oriented feature that was underused. In March 2016, after the removal was publicized and criticized in the wake of the FBI–Apple encryption dispute, Amazon announced that it would be restoring the feature in a future patch.