There are several ebook readers available for desktop Linux users.
Almost all distributions come with a document reader that can open PDF files. It may also support other file formats like epub or Mobi, but that’s not guaranteed.
This is why specialized applications like Foliate and Calibre are needed to read and manage ebooks in various formats.
Recently, I came across another open source software that boasts several exciting features for an ebook reader.
Koodo: It has all you can think of
Koodo is an all-in-one open source ebook reader with features to help you better manage and read your ebooks. It is a cross-platform app you can download on Linux, Windows, and macOS. You can even use it in a web browser.
The user interface looks modern, probably because it is an Electron app. You’ll have to import the books and add them to Koodo. It doesn’t import books by folders. You can select multiple files for import, though. Got too many books? Add some to your favorites for quick access.