SOS Online Backup is an easy-to-use online backup tool which can protect up to 5 devices - PCs, Macs, iPhones, iPads, Android tablets and phones - with a single account.

The straightforward client makes it easy to choose the files you'd like to upload. These can then be backed up just as soon as changes are detected, and the program's unlimited versioning means that older incarnations of documents will always be just a click or two away.

SOS Online Backup has plenty of bonus features. It can back up your Facebook account, for instance: photos, music, videos, wall posts, friends and more. And the service makes it easy to share any of your backed-up files. If it's just archived a home video which is too large to send via email, for instance, then you can always make it available to chosen friends and family. They'll receive an email with a link which they can use to view or download the file.

If you're more interested in making sure that no-one else can ever access your backups, though, there's no need to worry - SOS Online Backup is extremely secure. Your documents are uploaded via a secure connection, and encrypted at the data centre using 1024-bit AES. You can even tell SOS Online Backup not to store your password, which means only you will ever be able to restore your files (although you'll need to make sure you don't forget the password, as the company won't be able to send you a reminder).

As long as you do have your login details, though, viewing and recovering your files is straightforward. You can see them via your browser, on the iPhone, iPad or Android devices. And the SOS Online Backup client provides a "time machine" which allows you to go back to the date you want and recover whatever you need from that file snapshot.

What does this all cost? Prices start at $79.95 for a 1-year, 50GB account, and then increase depending on the length of contract and amount of storage space you need (3 years and 150GB is $249.95, for instance). If you want to sample the program's speed and ease of use, though, then download the client here and you'll have everything you need to set up a trial account.

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A fast and easy-to-use online backup tool with a stack of useful features