Amazon Kindle : FireOS

https://developer.amazon.com/public/solutions/platforms/android-fireos
https://developer.amazon.com/appsandservices/solutions/platforms/android-fireos
https://developer.amazon.com/public/resources/development-tools/sdk


Fire OS starts with Android at the core, adding:

• Low-level platform enhancements, including: the Optimizing Download Manager, a re-designed graphics pipeline, Reading Mode and improvements to touch latency for better performance.
• Deep integration of the hardware, software and services to deliver features such as X-Ray, the Mayday button, Second Screen and more.
• Built-in media libraries that provide instant access to music, movies, apps and games both stored on the device or in the cloud and that automatically sync between them.
• Content-first user interface, with both Carousel and Grid views.
• Cloud services like Whispersync, 1-Tap Archive and Cloud Collections.
• Productivity apps with enhanced email, document and enterprise support with hardware and software data encryption.