Spanning Sync is described as '3 is the one app that syncs both iCal with Google Calendar and Address Book with Google Contacts. It gives you even better control over how your information syncs, and is now up to 10x faster!' and is an app in the Office & Productivity category. There are five alternatives to Spanning Sync for Windows, Online / Web-based, Microsoft Office Outlook, SaaS and Mac. The best alternative is SyncMate, which is free. Other great apps like Spanning Sync are SYNCING.NET (Paid), OLContactSync (Free), SyncThemCalendars (Paid) and OLFolderSync (Paid).
SyncMate syncs data on Mac with Android and iOS devices, Windows services (Outlook, Office 365 Business and Office 365 Home accounts), other Macs, Google, Dropbox and iCloud accounts, any mounted storage devices, MTP devices.
SYNCING.NET offers powerful Data and Outlook synchronization for individuals, professionals and businesses. By providing secure PC synchronization, integrated file and Outlook sharing, users can access all their data at any time and any place.