Missing Sync is described as 'The Missing Sync from Mark/Space syncs smart phones and mobile devices with Mac OS X and Windows. You can sync Mac and PC to your phone' and is an app in the Backup & Sync category. There are six alternatives to Missing Sync for a variety of platforms, including Mac, Windows, Android, iPhone and Android Tablet. The best alternative is EteSync. It's not free, so if you're looking for a free alternative, you could try SyncMate. Other great apps like Missing Sync are AkrutoSync (Paid), BirdieSync (Paid), iSync (Paid) and Mobile Master (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.
iSync is a software application published by Apple Inc. It runs only under Mac OS X and is used to synchronize contact and calendar data from Address Book and iCal with many non-Apple SyncML-enabled mobile phones via a Bluetooth or USB connection.
Mobile Master is a mobile phone administration program and synchronization Pro for Sony Ericsson, Nokia, Motorola, Samsung, LG, Benq Siemens and iPod. Synchronize your phone data with your PC. Edit your phone book easily at your PC.