Best Open-Source Ebook Reader Apps in 2026

The ranking

1. 1
   

   Readest

   Open-source EPUB and PDF reader with apps on macOS, Windows, Linux, Android, iOS and the web, plus highlights, notes and text-to-speech. Kindle and Apple Books have longer track records.

   Best for Open-source reading across phones and desktops

   macOSWindowsLinuxAndroidiOSWeb·Free and open source·Open source

   86.5of 100

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2. 2
   

   KOReader

   Open-source reader for many formats that runs on Kindle, Kobo, PocketBook, Android and desktop Linux. It reads files you already have, but it does not sell books, so it suits readers who manage their own files.

   Best for E-ink devices and many document formats

   AndroidLinux·Free and open source·Open source

   85.0of 100

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3. 3
   

   calibre

   Free and open source library manager that converts books between formats on Windows, macOS and Linux. It is a desktop tool with no phone reading app, so it complements a reader rather than replacing one.

   Best for Managing and converting a large personal library

   WindowsmacOSLinux·Free and open source·Open source

   83.0of 100

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4. 4
   

   Thorium Reader

   Free, open-source desktop reader for Windows, macOS and Linux under BSD-3-Clause. It has no phone app, so it suits readers who only read on a computer.

   Best for Desktop reading of open-format books

   WindowsmacOSLinux·Free and open source·Open source

   80.0of 100

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5. 5
   

   Foliate

   An open-source ebook reader for Linux that opens EPUB and Mobipocket files, with auto-hyphenation, popup footnotes and media overlays. It is a reader, not a library manager, unlike calibre, and it runs only on Linux.

   Best for A simple open-source reader on Linux

   Linux·Free and open source·Open source

   79.0of 100

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