iMazing - iMazing lets you transfer music, files, messages, apps and more from any iPhone, iPad, or iPod to a computer, Mac or PC. Manage and backup your iOS device simply without iTunes. (was DiskAid)
calibre - Ebook manager, viewer & converter
plist Editor - Reads and writes both text and binary .plist files.
FBReader - FBReader is an e-book reader for various platforms. Features:
FileBrowser - FileBrowser is a multifunctional file manager for the iOS devices that are used for accessing files in both local and networked environment.
Google Play Books - Google Play Books lets you search, preview, and buy millions of books using Google Book Search.