[dwig]

Originally Posted by jbacelar

And for to build e-books.

Why do not you take a look at the Calibre editor's manual? (https://manual.calibre-ebook.com/edit.html) and so you can speak with real knowledge of the subject.

True. It is now somewhat of a "Swiss Army Knife" tool.

At its core, calibre is a library manager and format converter. It has grown over the years adding satellite apps for ebook reading and for true ebook editing. The latter being roughly the equivalent of Sigil. Sigil remains a rather "single minded" but powerful tool; its purpose being solely ebook creation & editing.