BitTorrent Sync is free software, available for all major platforms, that keeps folders in sync across your devices and enables you to share them securely with other people. That may sound suspiciously like Dropbox, iCloud Drive, and dozens of other cloud storage services — and indeed, the end result is much the same. The big difference is that BitTorrent Sync uses peer-to-peer networking rather than relying on cloud servers.
This approach has several significant advantages. You can have as much storage as you like (limited only by your local disk space) without paying a penny, and because your files are never stored in the cloud, no one else can access them without your explicit permission.
There are downsides too, though. At least one of the computers where your files are synced must be turned on and accessible to the Internet for you to access your files, and you'll be subject to your ISP's bandwidth and data caps. Although BitTorrent Sync encrypts your data as it travels between your devices over the Internet, it doesn't encrypt files on disk — if you want to do that, you're on your own. And you're unlikely to find many third-party iOS apps with built-in support for BitTorrent Sync, whereas support for Dropbox, iCloud Drive, and other cloud services is common.
For now, I suggest thinking of BitTorrent Sync as a supplement to cloud storage, not a replacement. Even though it has been available for nearly two years and is now at version 1.4, it's still considered beta. Although I haven't encountered any serious bugs, but some aspects of its user interface are still obscure or confusing, and setup requires a somewhat odd series of steps. I'll walk you through some of the basics.
Set up folder sync
Once you've downloaded and installed the software, BitTorrent Sync offers several ways to set up syncing between folders on your devices. I'll describe the simplest approach here; for other options, see the online help.
On a Mac that has a folder you want to sync, open the BitTorrent Sync app. Click Add Folder, navigate to the folder you want to sync, select it, and click Open. In the dialog that appears, select Read & Write under Permission (to let yourself modify the folder on any of your own devices). Click Email to create a new message in your default email client, address it to yourself, and click Send.
So far, you've merely made a folder available for syncing. The next step is to set up a peer — another device that will sync this folder.
To set up another Mac as a peer, open the email message you just sent yourself on that Mac and click the link. A webpage opens with two buttons. If the Mac already has BitTorrent Sync installed, click "I already have Sync 1.4." If not, click "Install Sync 1.4 Beta" to download and install the software, and then return to the page and click the other button. (As time goes on, the version number on the buttons will presumably change.)
Sign up for CIO Asia eNewsletters.