Calibre Portable software (version 0.8.24) is a free and open-source e-book library management software that allows users to organize, convert, and read e-books in various formats. It features a user-friendly interface, with the ability to customize font sizes and styles, and supports multiple languages. It can also sync with e-book readers and convert e-books to various formats for compatibility with different devices. Additionally, it offers features such as metadata editing, searching, and downloading e-books from various sources.