BTSync FREE vs BTSync PRO

Although both BitTorrent Sync 2.0 FREE and PRO ensure high file transfer speed and ultimate security, PRO version provides you with a lot more functionality:
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All Sync Versions
Fast transfer speeds
Private device-to-device communication
No folder size limits
Sync FREE	Sync PRO
Up to 10 folders at a time	Unlimited number of folders
-	On-demand access to files from desktop
-	Change access permissions on-the-fly
-	Sync All ON/OFF
-	Pro support

The total number of folders which can be kept synced via FREE version at a time is limited to 10.

If you have already added 10 folders, and want to add one more, you will have to delete at least 1 folder from the previously added ones or upgrade to PRO.

PRO version enables you to link all of your devices under a common identity.

This gives you access to ALL added folders on ALL of your linked devices automatically. Learn more

Sync on-demand lets you access files on other devices without actually syncing them in full to your device.

You can view folders, look through their contents and then fetch only those files you need.

Available on mobile platforms in the free product, on desktops this feature gets activated in the PRO version only. 

In Sync 2.0 PRO you can change access permissions (Read Only, Read & Write, Owner)

as well asrevoke access at any time from users you share files with (unavailable while sharing data via My Devices).

For example, now if you wish to upgrade Read Only permission to Read & Write,

you won't have to disconnect a folder and then reconnect it again passing a new key:

Sync will modify permission at the push of a button without breaking connection. 

In Sync 2.0 PRO, devices with large amounts of storage space (NAS devices, file servers, desktops, etc) can be toggled to 'Sync all.'

This will backup all of your Sync folders to an always-on device, providing continuous access to your files.

Both ​PRO and FREE users are encouraged to browse Sync Knowledge Base for the answers to their questions as well as check BitTorrent Sync Forum.

PRO users are provided with guaranteed support within 24 hours of their request.

FREE users are welcome to send their feedbacks - Sync support team will respond to them to the extent possible.

Important note on mobile platforms: 

Sync mobile app is free, and unlike desktop versions, it does not have folder or feature limitations,

however, connecting your mobile device to a licensed identity on a desktop will let you get the most out of your Sync.