A KFX file is an eBook created in the Kindle Format 10 (KF10), Amazon's successor to the .AZW3 (Kindle 8) format. It contains an Amazon eBook, which includes the text and metadata describing the book, such as the author, title, and number of pages. KFX files support enhanced typesetting capabilities that are not provided in previous formats, such as hyphenation, improved character placement and word spacing, and a more adaptable page layout and margins.
KFX file open in Kindle for Mac 1.2
eBooks may be saved in one of several formats. The format of an eBook downloaded from the Amazon store depends on the device being used to download and read the eBook. It may be saved in the KFX format or in the .MOBI, .AZW, or .AZW3 formats.
To open and view eBooks saved in the KFX format, Amazon provides a Kindle app for Windows, macOS, Android, and iOS. You can also use Calibre, a popular program for managing and opening various eBook formats.