Kindle File Format is a proprietary e-book file format created by Amazon.com that can be downloaded and read on devices like smartphones, tablets, computers, or e-readers that have Amazon's Kindle app.

Software such as the free and open source Calibre, Amazon's KindleGen,[2][3] and the email based Send-to-Kindle service are available to convert e-books into supported Kindle file formats.

Kindle devices can also display some generic document formats such as plain text (TXT) and Portable Document Format (PDF) files; however, reflowing is not supported for these file types.

[4] AZW3 supports a subset of HTML5 and CSS3 features,[5] while acting as a container for a backwards-compatible MOBI content document.

[6][7] In August 2015, all the Kindle e-readers released within the previous two years were updated with a new typesetting and layout engine that adds hyphens, kerning and ligatures to the text; e-books that support this engine require the use of the "Kindle Format 10" (KFX) file format.