KF8

KF8, short for Kindle Format 8, is Amazon's e-book file format introduced to replace older formats for Kindle devices. Debuted around 2011–2012 with the Kindle Fire tablets, KF8 uses HTML5 and CSS3 as its underlying markup language, enabling richer typography and layout than previous Kindle formats. Content packaged as KF8 is typically delivered in the AZW3 file extension, the packaging format for most modern Kindle titles.

Technical features include support for embedded fonts, expanded CSS capabilities, and advanced layout options. KF8 also allows fixed-layout books for certain genres such as children's titles and comics, enabling precise placement of text and images. The format supports international fonts and right-to-left scripts, aiming for more faithful rendering across Kindle devices and apps. As an extension of the MOBI/AZW ecosystem, KF8 preserves metadata and DRM if applied by publishers.

Compatibility and use: KF8 was designed for Kindle Fire devices and subsequent Kindle e-readers and apps, with older Kindles receiving limited or no KF8 support. Publishers publish KF8 titles to the Kindle Store; readers on supported devices receive the KF8 rendering. Conversion from other formats (for example EPUB) to KF8 has historically been supported through KindleGen and third-party tools, though modern workflows increasingly use Kindle Direct Publishing with KF8-ready templates.

Relationship to other formats: KF8 supersedes the earlier AZW/AZW2 formats for most new Kindle books. In later years Amazon introduced more advanced formats such as KFX, which offer further improvements in typography and compression, but KF8 remains widely used for many Kindle titles.