Apps like Calibre Sync

Here are some great alternatives to Calibre Sync by BIL studio :
CloudBooks audio book player
CloudBooks audio book player
★4.1
FE File Explorer Pro
FE File Explorer Pro
★4.5
Astiga - Cloud music player
Astiga - Cloud music player
★3.3
Sync - Backup and Restore
Sync - Backup and Restore
★3.4
Advance Online Storage/ Backup
Advance Online Storage/ Backup
★4.2
Air Explorer
Air Explorer
★3.5
Cloud Storage / Backup Data
Cloud Storage / Backup Data
★4.2
ContactSync trial
ContactSync trial
★5.0
ownCloud
ownCloud
★4.2
ContactSync - CardDAV and more
ContactSync - CardDAV and more
★4.9
DAVx⁵ – CalDAV CardDAV WebDAV
DAVx⁵ – CalDAV CardDAV WebDAV
★4.3
CalendarSync - CalDAV and more
CalendarSync - CalDAV and more
★4.0
floccus bookmark sync
floccus bookmark sync
★3.9
CloudPlayer™ cloud & offline
CloudPlayer™ cloud & offline
★3.6
Titanium Media Sync
Titanium Media Sync
★3.4
OneSync: Autosync for OneDrive
OneSync: Autosync for OneDrive
★4.6