Calibre is, bar none, one of the best tools I ever used. I acquired it originally for managing and converting my Kobo ebooks, but I was amazed at how robust its

Calibre is, bar none, one of the best tools I ever used. I acquired it originally for managing and converting my Kobo ebooks, but I was amazed at how robust its ebook viewer and especially ebook production tools were. I had an ebook that was clearly of dubious origin, as its Table of Contents page was completely broken (both the actual ToC page and the auto-generated navigation page). But all of the actual test was there. Once I opened the book up in the ebook editor, I was surprised at how quickly I was able to fix the ToC and change all the references to the correct chapter documents. It's a fantastic tool, and one of the few examples where I think the "kitchen sink" approach really works, as opposed to a collection of UNIX-style tools (although it has those, too).