If you want to sync your Kindle books, which are not purchased through Amazon, you can do so by using your Amazon account.
- Go to Amazon webpage and sign in.
- Move the mouse to the "Hello <your_name>" and you will see:
- Go to "Your Cloud Drive"
- Upload your file. Kindle uses .mobi format for books.
- Open up your Kindle app in your device and select cloud. The uploaded files will be available there.
