Calibre is mostly a single user desktop app but has calibre-server to share ebooks, although it might have some X dependencies. Installation example on Ubuntu.
Alternatives to calibre-server (but built to use a calibre database) are:
Other options to manage e-books:
- joyread (aka LibreRead, not stable, in its early stage of development)
- Moodle: moodle has a book module that can be combined with Lucimoo to import/export e-books.
- Nextcloud: Nextcloud has an OPDS catalog app and a e-book reader app.