Dropbox is the simplest, most elegant file-synchronization tool I've ever used. Dropbox Basic provides 2GB of storage free, and Dropbox Pro gives you 50GB for $9.95 per month or $99.95 per year. The service stores files with strong encryption on multiple servers in Amazon's S3 service and works equally smoothly on Windows, Mac, and Linux PCs. If you prefer to synchronize folders you already have on your system, or if you want to keep several folders fully synchronized between multiple machines, Dropbox may not be for you. It synchronizes only files stored in a single dedicated folder. But its smooth and hassle-free operation make it our Editors' Choice.
You start by signing up on Dropbox's Web site, then downloading and installing the client program. This creates a new folder called "My Dropbox" in your Documents folder (you can move it later) and a system tray icon that lets you open it with just a double click. From this same icon, you can also reach other preference settings, such as the folder's location and throttles on upload and download speeds. Another nice option on the pop-up menu is the "Forums" item, which opens a browser window on Dropbox's user support forum; you'll find the dialogue between users and developers livelier than on most competing services' sites.
Like its rival services, Dropbox stores synchronized files in the cloud so they're available at any machine on which you've installed Dropbox. You can also reach your files through a Web interface from any Internet-connected system. Dropbox's storage preserves copies of earlier versions of the files in My Dropbox, so you always have the most current copy on your computers. I liked that you can still access older versions (or files you deleted or moved) with just an Internet connection. One attractive feature (also available in SugarSync) is Dropbox's bandwidth-saving ability to upload and download only the parts of files that change during revisions. This isn't always possible, but I've made frequent changes in a 125MB file I synchronize and sometimes found that Dropbox needed to transfer only 2 to 3MB of data to update the file. That's a decent bandwidth savings.
When the installer creates the My Dropbox folder, it also creates a subfolder called Public. Files placed there aren't immediately visible to anyone, but by right-clicking on one and choosing the Copy Public Link, you create a Web address of a permanent, public link to the file that you can publish on the Web or send to friends or colleagues—even if they don't use Dropbox. (You should use this feature only for files you don't need to restrict to specific users, because there's no password protection.) I even built a small Web site in my Public folder by filling it with an HTML file and images and sending the link to friends so they could open it in their browsers. A similar feature with another subfolder called Photos lets you send a link to a Public Gallery that anyone can use to view any photos you've copied into it.
A slightly different feature uses invitation-only shared access to folders you create anywhere in My Dropbox. Right-click the icon of the folder you want to share, then choose an option to share the folder. The Dropbox Web interface opens, and you can send invitations to friends and colleagues that let them add, edit, or delete the files in the folder. They'll need a free Dropbox account, but they won't need to install the client if they're satisfied with accessing the folder over the Web. If they do install the Dropbox client, the shared folder will automatically download to their My Dropbox folder.
One major plus for Dropbox is its clean, intelligent design. When you right-click on a file in My Dropbox, you can choose the "Revisions…" option to start the Web interface and see a list of changes for that file. This is far more convenient than anything offered by SugarSync or Syncplicity, which force you to hunt down files you want in either a Web interface or a separate program and then choose to see revisions made to them.
The Web interface is clean and efficient—it looks a bit like Facebook without the clutter. At the top is a collapsible list of Recent Events listing files you've recently edited, added, or removed from Dropbox. You can even create an RSS feed of these recent changes, so you can be alerted to changes friends or colleagues make to shared files. Beneath the Recent Events is a list of your files, complete with icons for downloading earlier revisions of current files or deleted files, or removing files entirely.
I said earlier that Dropbox can sync only files in its Dropbox folder, but expert users can overcome that limitation fairly easily. On Vista (but not XP), Mac, or Linux, you can create a symbolic link inside My Dropbox to any file or folder anywhere on the system, and those files or folders will be synchronized as if they're actually in My Dropbox. Dropbox promises to add a "Watch Any Folder" feature in the future that will make it work in the same way its rival products do.
Dropbox is an example of software that gets virtually everything right—including automatic updating of itself when a new version appears. When the "Watch Any Folder" feature arrives, Dropbox will be all the more useful. Even without that ability, however, I was impressed enough to buy a year's subscription after testing it for this review. Dropbox is our Editors' Choice for file-synchronization services.
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