If you use multiple computers, file-syncing eliminates the need to transfer files using email or a thumb drive. When you make a change on a file on your work computer, for example, that file will automatically be updated on the service's online interface, your home computer, your laptop and the service's mobile apps. Three out of four file-syncing services discussed here offer free plans, with paid options if you need more storage space.
Dropbox (Free for 2 GB) has long been one of the most popular options among file-syncing services, earning Editors' Choice awards and accolades from almost all who review it. Its biggest rival, SugarSync (Est. $7.50 per month for 60 GB) is also well reviewed, but unlike Dropbox, it doesn't work with the Linux operating system and doesn't offer a free plan (just a 30-day free trial). That makes Dropbox our Best Reviewed pick for a well-rounded file-synchronization service.
If you reach your 2 GB limit, you can often earn more free Dropbox storage by recommending friends or helping Dropbox beta-test new features (up to 18 GB total). Otherwise, Dropbox offers paid subscriptions for 50 GB (Est. $10 per month) or 100 GB (Est. $20 per month). The service saves file versions for 30 days for all subscribers; premium subscribers can purchase the "Packrat" option (Est. $40 per year) for unlimited file versioning that will never be deleted.
Reviewers say Dropbox is a snap to use. Downloading the software takes only a few minutes, backing up your files is as simple as dragging and dropping them into the client, and Dropbox is also useful for sharing documents with others. In addition to the usual Android, Mac, iOS and Windows support, Dropbox is one of the few cloud storage services to support Linux computers and BlackBerry phones. Reviewers appreciate the cross-platform support, and you can sync files among computers with different operating systems.
As popular as Dropbox is, reviewers say that two synchronization services strongly challenge it in the cloud storage wars: Google Drive (Free for 5 GB) and Microsoft SkyDrive (Free for 7 GB). They offer more free storage space than Dropbox, and their premium subscriptions cost less. What's more, Google Drive and SkyDrive include very functional productivity tools that allow you to edit documents, spreadsheets, slideshow presentations and other files from within your browser -- and because it's all stored online, the two services include features that let you collaborate with others to edit files together in real time. However, neither of these services have true backup capabilities, although they do keep a limited number of older versions of your files.
If you have complicated file-syncing needs, SugarSync (Est. $7.50 per month for 60 GB) gives you more control over which files are synced. Unlike other file-synchronization services, most of which create a designated syncing folder on your hard drive, SugarSync allows you to handpick which folders to sync. It also backs up data whenever files are altered, and the last five versions of changed files are saved on the company's servers without costing the user additional storage space. That blend of features, combined with an intuitive interface and reasonable storage prices, wins over many experts. SugarSync is compatible with Macs, Windows PCs, and iOS, Android and BlackBerry mobile devices.
Dropbox offers a wide variety of plans and a generous free account (you can earn up to 18 GB free through referrals) and is a file-synchronization service that will please most users.