The best open source alternative to calibre is KOReader. If that doesn't suit you, our users have ranked more than 100 alternatives to calibre and many of them is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to calibre are Readest, Foliate, Librera Reader and Koodo Reader.
An ebook reader application supporting PDF, DjVu, EPUB, FB2 and many more formats, running on Kindle, Kobo, PocketBook, Linux and Android devices.
As an e-book reader it is unparalleled, I believe. It is not a feature-rich library management tool, though.
Readest is a modern, open-source ebook reader for Windows, macOS, Linux, iOS, Android, and the web.
Librera Reader is a highly customizable and feature-rich application for reading books in PDF, EPUB, MOBI, DjVu, FB2, TXT, RTF, AZW, AZW3, HTML, CBZ, CBR formats on Android devices.
Koodo Reader is a powerful ebook reader designed to provide a simple and easy-to-use reading experience.
cleaner and significantly better user interface and user friendly.
I use the web-based platform and it's just very good. Super intuitive and minimalistic but with great functionalities and customization. And it's FOSS.
Sigil is a multi-platform ebook editor. It is designed to edit books in ePub format.
Openlib is an open source app to download and read books from shadow library (Anna’s Archive). The App Has Built In Reader to Read Books.
Calibre-Web is a web app providing a clean interface for browsing, reading and downloading eBooks using an existing calibre database.
Episteme Reader is an offline-first application designed for reading various document formats. It leverages native Android technologies and C++ libraries to provide a performant reading experience with customization capabilities.
Lightning fast with a slick design, Kavita is a rocket-fueled self-hosted digital library which supports a vast array of file formats. Install to start reading and share your server with your friends. book reader, self hosted, manga, comics, free, manhwa, e readers, electronic...
Storyteller is a self-hosted platform for creating and reading ebooks with synced narration. It's made of three components: the API server, the web interface, and the mobile apps. Together, these components allow you to take audiobooks and ebooks that you already own and...
Thorium Reader is a free, open source multi-language EPUB reader for Windows 10, MacOS and Linux. It's privacy aware and highly accessible for visually impaired and dyslexic people.
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A very feature-full reading app. I use it with my PocketBook Color and PocketBook InkPad Color and it is much snappier than the default reading app.