When comparing FBReader vs Sumatra, the Slant community recommends Sumatra for most people. In the question“What are the best desktop readers?” Sumatra is ranked 2nd while FBReader is ranked 3rd. The most important reason people chose Sumatra is:
Sumatra is available for free, licensed under GPL with source code available on [GitHub](https://github.com/sumatrapdfreader/sumatrapdf).
Ranked in these QuestionsQuestion Ranking
Pro Simple and fast
FBReader, while offering many options is simple in design, with that allowing for fast use.
Pro Cloud sync
FBReader has built in Google Drive sync for the users files, allowing them to store their eBooks online, not taking up room on their local storage.
Pro Cross-platform and open source
FBReader is a completely free cross platform eBook reader that is also open source.
Pro Built in eBook store
FBReader features an in built eBook store for users to download eBooks onto their devices through the app.
Pro Free and open source
Sumatra is available for free, licensed under GPL with source code available on GitHub.
Pro Reads many file types
Including PDF, XPS, DjVu, CHM, EPUB, Mobi, FictionBook, PalmDoc, and comic books.
Pro Book updates on the fly
If Book font, style is changed, Sumatra will take the update instantly, No need to close first and import again! Huge time saver for self publishing.
The application consists of a single file that can be run without installation. You can put it on an external device, such as an usb thumb stick and run it on any Windows machine from the thumb stick.
It's available in 69 languages.
Con UI is bad
User interface is confusing and ugly
Con Complex and confusing app settings
Con Windows only
No Linux or OSX versions available.