Calibre 5.0
It's a big shame that whenever anything related to Calibre is posted, top comments will often be how arrogant is author is. I used to think the same. But when I read his comments history in GitHub, he doesn't seem a dick to me at all. So I googled his name, and end up in a forum. It completely changed my mind.Contrary to what people believe, Dovid Goyal is the most friendly programmer to his users. He spent lots of time answering questions in the forum https://www.mobileread.com/forums/forumdisplay.php?f=166. His answers include where is a menu located, how to convert a book from one format to another, helping the user to debug the exact the problem with Calibre. He has been doing this daily and is very responsive. You can expect an answer to your question in the same day. (The forum used to allow you to read user's comments history anonymously, but now you need a account to do so)