Calibre is a vibrant open-source community with half a dozen developers and many, many testers and bug reporters. It is used in over 200 countries and has been translated into a dozen different languages by volunteers. calibre has become a comprehensive tool for the management of digital texts, allowing you to do whatever you could possibly imagine with your e-book library. Reading is very important to me and one of my goals has always been to prevent either the fragmentation or the monopolization of the e-book market by entities that care solely for short-term goals. As the calibre community continues to grow, driven by book lovers, for book lovers, hopefully it will always present an alternative for people that love to read e-books and want to be in control of their own digital libraries.
site link: http://www.calibre-ebook.com/