One of the positives of Android e-readers is the flexibility that comes with the option to install third-party applications. One useful feature is the possibility to set-up two-way syncs between local and cloud storage. The two-way sync enables the opportunity to edit a PDF document locally to then to continue working on the same document on another device. Below are some options that make syncing possible:
Moon+ Reader Pro: Moon+ Reader Pro supports syncing via Dropbox and Google Drive. The application creates a directory in cloud storage that stores an e-book’s reading location and annotations.
FolderSync Pro: The application can be used to set up two-way syncs between local storage and a cloud service. It is essential, to access a document’s data across many devices, to store it within the synced folder to then access on another device with the same app (KOReader, for example, supports this feature).
I noticed that e-readers running on Android 6.0 don’t allow the stored documents to write to an external SD Card. To get writing to a sync folder to work, it is necessary, to enable two-way syncing, to either use internal storage or format and convert an SD Card to internal storage.
Installing the Kindle application or Google Play Books: It is possible to install the Kindle application to sync an e-book via Amazon’s cloud service. In my view, this is not a recommended option as the Kindle application is not designed for E-Ink. It is also possible to install Google Play Books and sync e-books through Google; again, like the Kindle application, the poor user experience makes this option untenable.
I found the best option for syncing e-books is to use Moon+ Reader Pro. Moon+ Reader Pro works relatively well on e-readers and opens e-books without delay. In comparison, KOReader can struggle with large e-books. The best option to sync PDF documents is to use KOReader – Koreader saves highlights in a PDF document and creates a directory to store the document’s meta-data.