calibre - Ebook manager, viewer & converter
Icecream Ebook Reader - Ebook Reader by Icecream Apps allows to read ebooks in several formats (EPUB, MOBI, FB2 and others). Download EPUB Reader for Windows.
Calibre Web - Calibre Web is a web app providing a clean interface for browsing, reading and downloading eBooks...
Komga - Media server for comics/mangas/BDs with API and OPDS support.
Ebook Reader - Ebook Reader-created and published by eBooks.
COPS - Simple OPDS / HTML content server for small servers.