Apple Books is described as 'The single destination for all the books you love, and the ones you’re about to. Browse the Book Store, join Oprah’s new Book Club, keep track of what you’ve read and want to read, and listen to enthralling audiobooks. All in one place' and is a very popular Ebook Reader in the news & books category. There are more than 50 alternatives to Apple Books for a variety of platforms, including Android, iPhone, Web-based, iPad and Android Tablet apps. The best Apple Books alternative is calibre, which is both free and Open Source. Other great apps like Apple Books are KOReader, Readest, Project Gutenberg and FBReader.
similar to ireader i was useing for my ipad