calibre: Cross-platform Ebook Manager
Summary
calibre is an open-source ebook manager that can view, convert, edit, and catalog ebooks across major formats. It can fetch metadata from the internet, interact with ebook reader devices, and even download newspapers for offline reading. The project is cross-platform (Linux, Windows, macOS) and maintained with documentation, development guides, and a bug tracker, licensed under GPL-3.0 with additional licenses for bundled components.