Cross-platform reading and syncing
I currently own a bunch of ebooks from various sources that I have collected over the years (as I have had an ebook reader for the past 10 years).
I also own readers on several different platforms: Windows, Android, and ios. I am looking for something that 1. I can upload my own books and 2. Can sync across all platforms.
Does anyone know if this exists? I have had some syncing success with Kindle, but I can't upload my own documents.
This would really be the holy grail of reader software.