Works on: Windows, Linux, Mac
DropBox is a free software to keep your files sync across multiple computers. Apart from that, it also keeps your files backed up on web, so that they can be accessed from anywhere. With a free account, you get 2 GB of free space to backup and sync your files.
I really like DropBox because of the ease of its use:
To use DropBox, just install the free DropBox software on all the computers on which you need to keep the files in sync. After installation, DropBox will create a folder on your computer. Whatever files you need to keep in sync or backed up, just drop them in this folder. Those files will automatically be kept in sync across all the computers in which you had installed DropBox. Apart from that, DropBox also keeps a copy of all such files on its secured website that you can access from anywhere, without a need for installing DropBox. Really cool!
Here are some of the features of DropBox that I like:
Sync only Changed Parts of Files: Whenever you make changes in a file, DropBox detects the parts of the files that have changed, and just syncs those parts. So, the syncing process becomes very fast.
Undelete Deleted Files: DropBox keeps a version history of all the files. So, even if you deleted a file, you can recover it from DropBox easily.
Very Easy to Use: DropBox is extremely easy to use. You do not need to learn anything in this. It keeps running in the background, and automatically takes care of syncing your files.
Safe: DropBox transfers data over SSL and encrypts with AES-256 before storage.
Works Across Multiple Platforms: DropBox keeps your files in sync over multiple platforms. So, you can be syncing your files across Windows, Mac, as well as Linux at the same time, and also keeping a copy in the free web space.
Access Files from Web: If you are not at one of your computers where you have DropBox installed but need to access your files, then it is very easy to do so. Just head over to DropBox website, login to your secure account, and you will see all your files there. You can download any of those directly, without a need to install DropBox. The best thing is that you did not have to do anything special to move the files to web in first place, they were automatically getting backed up there!
Collaborate on Files: You can set a folder in DropBox to collaborate with friens or fellow workers. Then they can also make changes in the files and they will be synchronized across all the computers.
Share files with Friends: If you want to share files with your friends, you can move to your public folder, and get an unique URL for each file. Then you can share the URL with your friends, and they can download the file without a need to install DropBox.
All these features make DropBox a very effective free software to keep your files in sync and backed up. You get 2 GB of space absolutely free. If you download using the link that I have provided below, you get an additional 500MB of space (and I also get additional 500 MB).