For years now, Dropbox has been pretty much the gold standard of cloud-based file sync. Such a simple concept is bound to have plenty of competition, and indeed, the market is swamped with companies vying to sync files between your networked computers and other devices. I've tested several of these (most recently, SugarSync) and so far, have always come away disappointed. AeroFS promises to change that, and may give Dropbox a real run for its money. Currently in free but closed beta, AeroFS is open to the first two thousand PCWorld readers to use a special invitation code.

The biggest difference between AeroFS and most other solutions on the market is that AeroFS doesn’t force you to use a central server with a file storage quota. After installing AeroFS and sharing a folder with a friend or colleague, both computers find each other on the cloud (even through firewalls), and start sending and receiving files directly, through an encrypted link.

In simple terms, this means there is absolutely no space limitation for the amount of data you can sync. Seeing as how Dropbox currently charges $20/month for a 100GB quota, this is a big deal.

I tested AeroFS by installing it on two systems; one is a mid-range desktop machine, and the other a four year-old Toshiba laptop. The laptop was in a remote location, connected via a slow connection and through a dedicated Checkpoint firewall. File sync started as soon as I copied a file into the AeroFS folder, and the simple status dialog showed me exactly how the transfer is going. I synchronized a 150MB file over this link without a hitch, and with impressive speed. I also tested AeroFS on a local LAN; because it was a local link, file sync was very fast, clocking in at around 1MB/s.

Because AeroFS does not use a central server by default, you lose one key Dropbox feature: file versioning. Dropbox lets you roll your files back to a date in the past, something I've used on more than one occasion to revert program configuration files to a healthier previous state. When using AeroFS, you may have to handle file versioning locally on each machine with a backup solution like Oops!Backup.

The AeroFS Beta I tested did include a rudimentary option to synchronize files to a central AeroFS server for safe-keeping in the cloud, albeit with a limited storage quota. The company just added a versioning option for libraries synchronized to the central server (making it "just like Dropbox"), but it didn't work when I tested it; such is the way of the early Beta.

The thing that impressed me most about AeroFS was that file sync between computers just worked. I can only hope it remains as effective and nimble in the future; I will be using it for sensitive files I want to sync between my machines but keep out of the cloud.

--Erez Zukerman