About that Amazon EPUB3 option

Sean Fenian — Sat, 12 Sep 2026 22:03:42 GMT

A while ago, Amazon added a capability to offer eBooks published via KDP as DRM-free EPUB3 files as an alternative to native Kindle KF8 format. We at Fenian House immediately updated all of our eBooks to offer the EPUB3 download option.

It has just been brought to my attention by a reader that, well… to be blunt about it, Amazon does a lousy job of generating the EPUB3 downloads. In fact, even when a book is originally uploaded to KDP IN FULLY VALIDATED EPUB3.3 FORMAT, they throw that away and generate their own EPUB file from the Kindle KF8 file. And they generate it badly. Amazon-generated EPUB3 files do not pass W3C EPUB3.3 validation, and throw away much of the book's metadata. (I suppose I shouldn’t be terribly surprised by this.)

If you have bought any Fenian House eBooks in EPUB3 format from Amazon, and this non-compliance is a problem for you, please contact us with some form of proof of purchase/ownership, and we will provide you in return with a copy of the latest up-to-date EPUB3.3-validated book.

Additionally, if you are a Unix/Linux or Mac user, there exists a Python tool called KindleUnpack which does a far better job than Amazon does of generating an EPUB3 file from a Kindle KF8 file. There are caveats; don’t use it blindly on any Kindle book and expect clean results. However, it should work on any Fenian House eBook purchased in Kindle format, as all Fenian House books are uploaded to Amazon as fully validated EPUB 3.3 in the first place.

(I wish to personally thank reader Timothy Wynn for making us aware of this.)

Fenian House Publishing (Posts about eBooks)

About that Amazon EPUB3 option