Calibre offers you a unique solution to all your e-books needs. Simple, easy, cross-platform and open source, Calibre has been designed to be the best tool to manage e-book. The program includes a complete solution for e-library, format conversion tool, built-in e-book viewer and an e-book synchronization feature. Calibre is resulting from Unix environment, which means that it is structured of small pieces, each of them has its own command line interface and each feature can be re-used not only in the Python programs but also in any software. Calibre is developed by Kovid Goyal.