Gitden Air in combination with Gitden Reader provides a authoring tool to simultaneous see what the eBook will look like on several platforms.
EPUB 3.0 authoring, testing and validating epub publications on multiple devices simultaneously. It supports every EPUB tool there is including InDesign, Sigil, TextEditor, so once edited and saved it is displayed on the actual device. Gitden Air runs on a Windows based PC.
Gitden is a Korean company.
 Gitden Reader
Gitden Reader is an ePub 3 reader (also supports ePub 2), that can be remotely controlled by Gitden Air to display pages simultaneously on several devices of differing sizes, all running Gitden Reader. Both flowing books and fixed layout ePub books are supported for ePub 3. Gitden Reader is available for iOS, Android, source on Windows.