GitHub - koreader/koreader: An ebook reader application supporting PDF, DjVu, EPUB, FB2 and many more formats, running on Cervantes, Kindle, Kobo, PocketBook and Android devices
BookPub: EPUB Reader - Apps on Google Play
GitHub - BasioMeusPuga/Lector: Qt based ebook reader
Foliate — A simple and modern eBook viewer for Linux desktops
GitHub - caesiumstudio/csBooks-updates: csBooks is the best epub reader, pdf reader, mobi book reader and djvu reader for windows, linux and mac os. It solves your problems if you need ebook manager,