Kindle ebook for free distribution: azw3 or mobi?

Question

I'm working on a project of a website where we'll give ebooks for free (and of course without drm). Apart from epub, we'd like to give also a kindle-compatible format. And here I'm a bit confused:

• on one side, Amazon doesn't support anymore mobi for upload on their platform;
• on the other, kindle devices still read mobi -- and of course don't read epub;
• somewhere I've read of problems in sending non-amazon-produced azw3 files by email to a kindle.

I see that most ebook platforms give epub and mobi. Perhaps because the change on Amazon is recent? I wonder what is the best option for a new project.

Answer 1

I cannot answer with a technical comparison of the various formats because I have no technical knowledge of them, only some practical experience.

Afaik, all distributors (and publishers) other than Amazon itself, that make ebooks available for the kindle, use the MOBI format. That includes TOR, Smashwords, Arc Manor (Phoenix Pick), Humble-Bundle, Story-Bundle, Wildside Press (and Blackcat), Book Funnel, ... and I am forgetting several others (I buy mostly SFF books, so that restrict my exploration of the market).

Actually after 5 year of looking for ebooks sources, I know only Amazon as a distributor of azw3 (or other letter-digit combinations). And my experience with Amazon is only an endless struggle with format decoding problems. But there seems to be one constant : the kindle does accept the MOBI format.

According to the article you reference, it will continue to do so: "Amazon will still be delivering MOBI files to Kindles". They say nothing about other Amazon formats.

You remark that Amazon doesn't support anymore MOBI for upload on their platform; That is mostly true, but only because they switch upload to EPUB. Afaik, their other formats were never used by authors to upload books. They wre only for download.

My opinion is that sticking to EPUB and MOBI is the safe choice. Actually it may be the only technically available choice. Since everyone, other than Amazon, is using MOBI for the kindle, there is probably no market for software that would give other options.