' SumatraPDF ', which is released as an open source, is a simple and lightweight PDF reader that can quickly open PDF files and also supports EPUB , MOBI , FB2, CBZ, CBR, and image files used as e ...

Kindles used to only support limited file types, but as of 2022, they officially started supporting EPUB files. Now you can ...

Calibre is a free, open-source e-book manager that lets users convert EPUB files to Kindle-readable MOBI files. Here's how to use it: Download and install Calibre.