Sigil is an open-source multi-platform EPUB eBook Editor. Sigil supports code-based editing of EPUB files and the import of HTML and plain text files. A companion application, PageEdit, allows WYSIWYG editing of EPUB files.
FBReader Book Network
FBReader Book Network is online storage for your electronic library. If you use FBReader for Android or/and FBReader for iOS, the FBReader book network is a way to synchronize data across several devices.
Greenstone is a complete digital library creation, management, and distribution package. It provides a way of organizing information and publishing it on the web or removable media.
BiblioteQ is a professional archiving, cataloging, and library management suite. The software is available for all major operating systems and should be compatible with any system that supports Qt.
Calibre is a powerful eBook Management System that helps you view, convert, edit, and catalog ebooks of almost any ebook format.