Fire OS 5

Based on Android 5.1 "Lollipop",^[10] it added an updated interface. The home screen has a traditional application grid and pages for content types, as opposed to the previous carousel interface. It also introduced On Deck, a function that automatically moves content out of offline storage to maintain storage space for new content; the Word Runner speed reading tool; 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, and an Activity Center for monitoring children's usage.^[11][12][13] It removed support for device encryption, which an Amazon spokesperson stated 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 it would restore the feature in a future patch.^[14][15]

Fire OS 6

Based on Android 7.1.2 "Nougat", its main changes and additions include:^[16]

• Adoptable storage, allowing users to format and use their SD card as internal storage
• Doze/App standby, aiming to improve battery life by forcing devices to sleep when not actively used, adding restrictions to apps that would normally continue to run background processes

MediaTek exploits (2019)

In early 2019, security exploits for six Fire Tablet models and one Fire TV model^[17] were discovered that could allow temporary root access, permanent root access, and bootloader unlocking^{[note 1] [18][19]} due to security vulnerabilities in multiple MediaTek chipsets.^[20][21][22]

Fire OS 7

Based on Android 9.0 "Pie",^[23] it was released in 2019 for all 8th-11th generation Fire tablets.

In February 2022, Amazon announced that the Docs app would be replaced (in August 2022) by document creation functionality in the Files app;^{[citation needed]} and introduced an improved home editing system.^[24]

Fire OS 8

FireOS 8 is the latest release of FireOS for 12th generation fire tablets, based on Android 11, information about the release became available via Amazon developer documentation around May 2022.

FireOS 8 incorporates changes from Android 10 and Android 11, such as TLS 1.3 support enabled by default, High Efficiency Image File Format (HEIF) support, Dark mode, One-time permissions, Sharing improvements, Device auto backups (user needs to opt-in to device backups), etc.

Although it is noted in the Amazon developer documentation that some Android 11 features such as File Based Encryption (FBE) are not supported yet.^[25]

Report of migrating away from Android

Around November 2023, a report surfaced of Amazon's plans to migrate away from Android to a custom Linux-based operating system known as "Vega". Apps will be HTML5 based, specifically using React Native. Amazon was reported to be developing the operating system since 2017, and planning to launch TVs running Vega OS in 2024. It is unclear on whether existing Android-based Fire TV devices will get replaced with Vega OS.^[26][27]