Looks interesting. Does it support epub3 series?

Any plans to move beyond reading to also allow writing metadata?

Does this also provide an api to paginate and provide text and images from the ebook?

This looks exciting! What are the key improvements over the ebooklib python package?

I feel like mupdf probably fulfills this and very much more.

Personal plug: https://github.com/lalitshankarch/Qitab

This is a small EPUB reader I made that uses the system Webview to render EPUB documents!

Calibre ships with some useful command line tools for dealing with ebooks. ebook-meta allows you to inspect and alter ebook metadata, and ebook-convert can convert various formats between each other. This functionality is also exposed in the Caliber GUI of course, but that can be an.. acquired taste.