I have an old Kindle Reader from 2012 that I use pretty often. The problem I have with Kindles is that they don’t support epub books, only mobi. Sometimes I’ll download someone’s ebook and want to have it on my Kindle, and most processes for converting the files are pretty crappy and time consuming.
Enter Kindlegen.
It’s a super easy application you run from the Terminal to convert epub formatted ebooks into mobi formatted ebooks, and it’s free!
To run kindlegen, just download it from the link above, and open up a Terminal, and do this:
/path/to/kindlegen /path/to/book.epub
And that’s it! You now have a newly formatted mobi book ready to go for your Kindle.
Nice! I use an application called Calibre to manage my book library. It allows you to sort, filter, and quickly search through your ebooks, and it also includes tools allowing you to convert ebooks from one format to another, as you copy them to a device. You don’t really have to think about the device or the format, it knows when you plugged in a Kindle, and will convert to the right format as you push your ebook to your Kindle.
The interface is really dated, but that’s a good little software, I’d highly recommend it.