If you're a woman and you make jokes about how women should be at home cleaning not being engineers, it's not 'fine', it just makes you a dickhead. The only close competitor is Foliate, which is not cross-platform like Calibre, and even then it simply lacks many useful features that I rely on with Calibre, despite having a much cleaner UI. That's really what most people need out of e-book software, but Calibre really does go above and beyond any e-book software on the market right now. Adding books is trivial, as is editing metadata, and the reader itself is splendid. It's very easy to set up, as all you do is either point to a pre-existing library of files or create a new one. I'm perplexed as to whether some of the people in this thread and I are using the same software. It's rarely buggy, fast, logical to use, very feature-rich, and rather customisable. It is hands down one of the most useful programs on my computer. The proof of the pudding is Calibre itself, which is a joy to use. Add to the fact that he eventually fixed every bug in that thread as well as second-language difficulties that he likely experiences, and the vitriol that people have for him is undeserved. His only 'crime' was being blunt with a bug report around eleven years ago, and I'm struggling to see why people are so myopic as to turn that into their entire perception of him. He's very patient and kind with beginners, responsive to feedback, and rarely loses his cool with anyone. Anyone who has spent a decent amount of time on the mobileread forums will also know him as a remarkably intelligent, dedicated, and all-round fantastic guy. Kovid puts in an extraordinary amount of work (nearly 80 hours a week) into Calibre - of which most is for free, in the name of open source software. I must admit, I'm slightly shocked at some of the comments here. This comment is from the perspective of a Calibre power-user, and someone who has been involved with the software for years now.

Calibre software platform