The core functionality is based on FBReader source code with a few modifications. Books are imported from the Downloads folder, where they are saved by the browser or email client. Alternatively, you can manually copy your books to the Documents/Books directory under the home folder. Removable storage is supported as well, the books are stored in the /Books directory there.

In theory, it should be able to handle all E-book formats supported by FBReader. Tested mostly with epub and fb2.