Apparently, Kindle devices/the Windows/Mac apps, and Android all support KF8 more or less completely, but on iOS, an AFK file is used that does not support all KF8 features (discussion here).

Is there a list of what isn't supported on iOS somewhere? It's driving me crazy because I test on a Paperwhite and it's fine, but then I test on an iPad and things are broken...

  • You probably should let us know what specific formatting issue you are having. Commented May 13, 2018 at 12:58

2 Answers 2


I haven't tested on ios for a few months, but my experience has been that the differences between ios and other platforms in the last 2 or 3 years have reduced considerably.

A while back I compiled a list of the included fonts for each platform (including ios). What are serif and sans serif fonts on different ebook reading systems?

When I test on ios, I don't sideload anymore. I found that uploading through the Kindle Manage your Content and Devices is sufficient.

The main issue I encountered with Kindle on ios is that your styles don't work on larger displays (and that affects image sizing and placement). For that reason you need to use css media queries to differentiate between display sizes. I wrote which breakpoints I used on this thread (ignore everything but the last Update section) https://ebooks.stackexchange.com/a/6027/417

Some advanced designers/testers will note more subtle differences in support, but generally if reference the font correctly, handle images ok and used css media queries and have good fallbacks, everything will be sweet.


A discussion on the MobileRead forums from user jhowell offered this information:

  • KFX minimizes differences among devices, but this format is language-specific and is not available for Asian languages (Chinese, Japanese) yet.
  • The iOS pre-KFX format is based on the same format used for Kindle Cloud Reader.

In my case, I found the following differences between KF8 on iOS and the broader Kindle ecosystem:

  • CSS floats and margins behave somewhat differently
  • image background color is not supported

This is not an extensive list; these are just my notes after working on this for a few days.

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