Er, okay. So, if I am to understand the OP correctly, he needs to be able to sync ePubs across his devices.
There is already a cross platform tool in existence since 2014 that already does this exact same thing: Google's Play Books.
You can upload a DRM-free EPUB to Google's servers and have access to it across your devices, including the Mac OS X, Windows and Linux (in the form of Chrome Web Apps or just a normal web interface), Android and iOS. It supports annotations sync, progress sync and even plays nicely with book metadata. It's worth checking out in my opinion.
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