Stacks
I’m making Stacks, an open source ebook manager and server, as a lightweight alternative to Calibre. Written in Swift, it consists of a SwiftUI browser and a Mac/Linux server and CLI. Shares are automatically discovered via Bonjour/avahi and also published as OPDS feeds. It can import Calibre libraries and has basic support for managing books on Kindles, but I’ve only tested it with a MTP Paperwhite as that’s all I’ve got. https://github.com/MattKevan/Stacks