calibre

Really excellent multipurpose program for ebooks. Here in sourceforge it is classified as "cataloguing" software, but I suspect the majority of users use it to convert ebooks from one format to another. For example, you can convert back and forth between mobi (Kindle), epub, lit, pdf, lrf, rtf, and txt file formats. For users who have more than one kind of ereader this can be an invaluable tool to be able to keep ebooks on mulitple devices. Yes, it is also a cataloging program, and for some users it provides the best ebook catalog available, superior to the software provided by ebook devices. It can also be used as an ebook reader, as it will allow the user to open and read each ebook that has been added to the Calibre library. It has additional features, but those top 3 are the biggest draws for most people. Oh, I suppose it doesn't hurt to add that at this time there is no other program available that can substitute for its main features.

— VicL

I installed the latest version of Calibre after reading all of the great reviews, and I've had nothing but trouble. It runs slow. Painfully, insufferably and uselessly slow. In fact, I can't do much past loading the main screen before it completely locks up my system. Well after ~5 hours, 2 re-installations (same and older, 'more stable' version...0.7.17), 5 forced restarts, 1 windows failing to start (never seen before)...I give up. I've tried pretty much everything to try to get this working. (includes disabling firewalls & antivirus, and every other 'fix' there has been to this problem) I'm running windows 7 on a computer more than capable of handling whatever program I throw at it - except this one apparently. Every time a user (like myself) reports this problem, the developer swiftly dismisses it as a user-end problem...so if this happens to you, instead of spending hours of messing around just uninstall and move on.

— Kacknoob