Dropbox is the most important application I use because it keeps all my files in the cloud, syncs them across devices, shares them with my team and backs them up. It's spoiled me, because now I expect all my applications to be in sync no matter what computer I use.

The problem with native software (as opposed to web-based software) is that your data is stored locally. If I use an app for an hour on my desktop then pop open my laptop, I can't expect to open the same app and see all the data I just worked on because it's a different computer.

Several applications circumvent this problem by syncing your data with Dropbox or another online source. 1Password and Things are good examples of Dropbox support, while an app like Evernote syncs your data with it's own servers.

For apps that don't have a way to sync your data, there is a slightly less perfect (see below) solution at your disposal. It's worth trying if you don't have another way to keep things in sync.

In this example we're going to sync the Address Book application, so that your contacts are available on any computer you have setup with Dropbox. The same steps are involved in syncing most any other Mac app also.

Step One

Close the application you want to sync. Then click on your home folder and navigate to Library/Application Support/. Drag the AddressBook folder into your Dropbox. You can put the folder anywhere.

Step Two

Open the Terminal application. Type in:

cd ~/Library/Application Support/	

This just tells Terminal to "change directory" and navigate to the Application Support folder we were just in.

Step Three

We're creating a "symlink", aka a symbolic link. It's sort of like creating an alias in OSX, but an alias won't solve our problem in this case.

Now type this code in Terminal:

ln -s ~/Dropbox/AddressBook .

This creates a symlink permanently connecting the AddressBook folder in your Dropbox with the AddressBook folder in your Application Settings.

Step Four

Test your symlink by navigating to Library/Application Support/Address Book in the finder. If you see the files, your symlink worked!

Now your Address Book is being synced with Dropbox! The only thing you have to remember now is to not open the application on another computer until your Dropbox has finished syncing. Opening the app before it syncs can sort of blow everything up, which is what makes this solution shaky.

Deleting a Symlink

Keep in mind the actual files are now being stored in Dropbox. The AddresBook folder in Application Support simply points to those same files. So if you want to undo everything we just did, you can delete the AddressBook folder in your Application Support folder. Then move AddressBook from your Dropbox back to it's original location in Application Support.

I use this solution to sync applications like Billings or even my iTunes music library. Hopefully it can help if you use multiple computers. Rest assured that in "the future" stuff like this will get much easier as software becomes more web-connected.