KFX vs AZW3: Which Kindle Format Should You Use?
KFX and AZW3 are both Amazon Kindle formats, and they are easy to confuse because they look identical from the outside — same store, same devices, same ecosystem. The difference is who controls the file. KFX is Amazon's delivery format: it arrives from the Kindle Store, it is DRM-bound, and it is not something you can produce or convert yourself. AZW3 is Amazon's sideload format: it is what you get when you convert an EPUB or MOBI yourself, and it preserves the formatting you approved. One sentence settles most decisions — you use AZW3 when you bring your own books, and you only ever receive KFX when Amazon brings one to you. This guide explains what each format actually is, where you encounter them, and the few situations where the choice is genuinely yours. For the wider family of Kindle formats, the Kindle formats explained guide covers the full map.