Nothing sucks worse than getting to the office in the morning and realizing you left the most recent copy of an important file—whether it's your to-do list or a PowerPoint presentation—on your home computer. No matter where you are and what computer you're using, you always want the most updated set of documents and files you've got without having to carry 'em around on a thumb drive. Luckily, several free solutions can automatically sync folders between computers—even over the internet, through office firewalls—no matter what operating system you use. Whether you want work files edited at home to magically appear on your PC at the office, or the family room Mac to have a copy of the latest batch of digital photos downloaded onto the computer in the den, three free applications can help.
Sync Folders over the Internet with FolderShare (Mac and Windows, Free)
If the two computers you're working with aren't on the same local network and aren't both Windows machines—such as your home Mac and your office PC—you can still sync files between them over the internet using a free service called FolderShare. (We've already run down quite a few uses for FolderShare, from maintaining a consistent workspace, to syncing your Firefox extensions and Greasemonkey scripts between computers.)
If you haven't tried out FolderShare yet, here's how to get it set up:
On the first computer, download the appropriate FolderShare software for your system (either for Mac OS X or Windows) and install it. If you don't already have a FolderShare account, set one up using the installation wizard; you just need an email address and password. You will also assign your computer a name that FolderShare will use to refer to it. Make it something descriptive, such as "Work PC" or "Home Mac."
If you're running a firewall software like Windows' built-in firewall, when you complete the FolderShare installation, you may get a message asking whether the firewall should allow or block connections to and from FolderShare. For FolderShare synchronization to work, you must allow FolderShare traffic through your firewall.
On the second computer, repeat the same process. But when it comes time to set up or enter an existing account, choose "I've Already Created An Account" and enter the email address and password you set up in Step 1. If your second computer's firewall also asks, you will have to allow FolderShare through its firewall like you did on the first.
After FolderShare is set up on two computers, you're ready to start syncing folders between them. In Windows, click the FolderShare icon on the system tray and choose My FolderShare from the menu. The FolderShare web site will launch. Log in and click the "Create a personal library" link, as shown.
From here, you can choose a custom folder path or choose from commonly used folders, such as My Documents, My Pictures, or My Music to create your new library. After you've created the library, FolderShare will prompt you to sync it to another computer on the account, as shown.
Click the destination computer's name and navigate to the folder where you'd like files to sync, and press the "Sync Library Here" button. Then, choose which syncing method you want to use: Automatic or On-Demand.
Then click the "Finish" button to let FolderShare begin doing its thing. Any time you copy a file to a FolderShare folder on one computer, automatically in the background it will copy that file to the mirror folder on the remote computer. In my example, work files modified on the desktop or laptop will always stay in sync, regardless of location. As long as FolderShare is running and the computer is connected to the internet, the files will update. Note: FolderShare isn't completely unlimited—there's a 2GB individual file size and a 10,000 files per library limit on FolderShare synchronization.
Update, 7:00 PM, 3/26/2008: This post originally appeared in the new edition of the Lifehacker book, Upgrade Your Life. Since the book manuscript was completed—in fact, just a few weeks ago—FolderShare saw an upgrade, so this post has been updated to include screenshots from the most recent beta. Apologies for the old screengrabs that originally published.
Sync Files to Your PC on a Local Network with SyncToy (Windows only, but can sync to any shared folder)
Free Windows utility SyncToy is a simple tool that synchronizes files between two folders (located on the same PC or on different computers). Download the SyncToy 2.0 beta and install it on one PC that will be syncing with another. Start up SyncToy and click "Create New Folder Pair" to define a "Left Folder" and a "Right Folder." Files will initially sync from left to right, so choose the folder with the source files on the left and the destination on the right. If you're syncing to another computer entirely, you will need to share the folder so that your computer can open and save files to it. (Here's more on how to share files from a PC, and how to share a folder on a Mac.)
After you've chosen the Right Folder on the other PC, click the Next button. Select Synchronize as the Folder Pair action, and click Next to name your pair something descriptive, such as "Family room photo sync." Click the Finish button.
From here, you can configure, test, or run your new folder pair action, as shown.
Set SyncToy Action Options
To exclude any files from the synchronization action (such as system files, or maybe non-image files), click the "Change Options" link. There you can exclude files by name, extension, or subfolder; exclude hidden or system files; save overwritten files in the Recycle Bin; and choose other settings for your pair, as shown in the options dialog below.
Dry-Run Your SyncToy Action
When you're satisfied with the synchronization action options, it's time to try the synchronization. Because you'll be copying large numbers of files and you don't want to accidentally overwrite anything important, you can preview the results of the sync without actually running it. Click the Preview button to see what files will be copied from where and to where, given your action specs. Adjust your action as needed. If you don't want to synchronize folders, you can also Contribute or Echo from the Left Folder to the Right Folder to perpetuate actions on the Left Folder to the Right without mirroring the contents exactly. See SyncToy's help menu for details on what the Echo and Contribute actions do.
When you're happy with the results of your SyncToy action's Preview, it's time to give it a try. Click the Run button to perform the sync between folders. You can set up any number of folder pair actions in SyncToy to copy any number of folders to any number of other computers. The other computer doesn't have to be a Windows PC; Windows just needs to be able to browse to it to select it as the Right or Left Folder in SyncToy.
After you've set up SyncToy, each time you work on files in one place, you don't have to copy them manually but instead can just run your SyncToy action to update the folders elsewhere. That is, on either the family room or den PC, you can run a SyncToy action that copies the latest digital camera photos with one click.
Sync Files Between Computers at the Command Line with rsync (Windows, Mac, Linux)
Lifehackers comfortable at the command line who want scheduled syncing between computers on the local network or over the internet can do it using the old-school command line utility rsync. Rsync comes built-in to Linux and Mac OS X, and you can download it for Windows for free (using a Unix emulator like Cygwin or on its own). Rsync requires manual configuration and some mucking with IP addresses, firewall ports, and other fun stuff if you want to use it over the internet, so I recommend it only to those who speak CLI and are comfortable rolling up their sleeves. Here's a detailed primer on how to mirror files across systems with rsync.
If you regularly sync files over the network, pick your poison:
Are you a FolderShare/SyncToy/rsync user? What do you like or dislike about the software? Tell us what you think in the comments.
Gina Trapani, the editor of Lifehacker, likes her data synchronized and redundant. Her weekly feature, Geek to Live, usually appears every Monday on Lifehacker (except today). Subscribe to the Geek to Live feed to get new installments in your newsreader.