Types of cloud storage
Experts agree that all computer owners should use some kind of backup system to protect their important data. If your files are stored only on your computer, you are just a theft, fire or hard-drive failure away from losing everything. Cloud storage services, also called online backup services, are a good alternative to using CDs, DVDs, flash drives or external hard drives, though most experts recommend backing up both locally (to an external hard drive or flash drive) as well as to an online service for absolute peace of mind.
Cloud storage services allow users to store their most important or largest files (such as music and video) on a secure remote server or transfer them to other devices linked in a network. Most services have the same basic features: They allow you to either manually select files to back up or schedule a full system backup. The majority do incremental backups, storing changes to a file that's already backed up on the system within a short time after the change is made (ranging from seconds to hours). Most cloud storage services also offer file versioning, so you can restore older versions of your files, if needed.
More and more cloud storage services now specialize in synchronizing your files across multiple computers and mobile devices, and offering features that let multiple users collaborate and edit files. If you don't have many files, some leading cloud storage providers provide free accounts starting at 2 GB. That's enough to store about 200 MP3s or hundreds of digital pictures. Some of the top file synchronization services up that amount to 7 or even 15 GB, and following a major price cut by Google Drive (15 GB free; $2 per month for 100 GB; $10 per month for 1 TB), storage has become cheaper than ever.
If you need more space, paid monthly or annual subscriptions offer more storage. This is good choice if you want to back up the contents of your entire computer. Many cloud storage services create local backups as well, automatically copying your data to an external hard drive or another computer as well as to the company's servers.
While the cloud storage market used to be dominated by smaller companies like Mozy, Backblaze and SugarSync, bigger players like Google, Apple, Amazon and Microsoft are taking over cloud storage by offering impressive collaborative features (like Google Drive) or easy-to-use cloud services that are built into operating systems (like Microsoft OneDrive). Box, one of the earliest cloud storage companies, is still a major player as is Dropbox, perhaps the best-known online backup provider.
With privacy and security becoming bigger concerns for consumers and businesses, however, cloud storage companies are tightening encryption and other security measures. SpiderOak (Best Cloud Storage for Privacy and Security) bases its entire business model around privacy and security, and doesn't even keep a copy of your password or file names.
We found a number of good reviews for cloud storage services, but details can get outdated quickly. As a result, we focus on the most recent reviews from established tech websites running test reviews or providing details on storage services. User reviews are scarce because most of these services aren't sold by third-party retailers, meaning there are few places to post user reviews, though most cloud storage service reviews have a multitude of comments from users.
Best Cloud Storage
Beyond backup: Cloud storage with syncing, collaboration and free storage
When it comes to cloud storage, users are spoiled for choice. Collaboration features, cheap (or even unlimited) storage, pure online backup, privacy -- you can easily find a service that meets your needs. With so many options (including dozens of cloud storage companies touting everything from free storage to syncing), choosing a single service can be overwhelming.
Aside from simply backing up files in the cloud or to other devices, file syncing is a key feature of many cloud storage providers. If you use multiple computers, automated file syncing eliminates the need to transfer files using email or a thumb drive. When you make a change to a file on your work computer, for example, that file will automatically be updated on the service's online interface, your home computer, your laptop and the service's mobile apps.
Dropbox (2 GB free; $10 per month for 100 GB) is arguably the most well-known file syncing and online backup service, and is our pick for Best Cloud Storage. It's incredibly easy to use, with an intuitive interface and file syncing that lets you store and access files on multiple computers, mobile devices and in the cloud. Downloading Dropbox takes only a few minutes, and backing up your files is as simple as dragging and dropping them into the client. It's one of the few companies to work on Windows, Mac, Linux, iOS, Android and even BlackBerry. Reviewers appreciate the cross-platform support, and you can sync files among computers with different operating systems. The service saves older file versions for 30 days for all subscribers; premium subscribers can purchase the "Packrat" option (Est. $40 per year) for unlimited file versioning that will never be deleted.
Google Drive nips at Dropbox's heels
As popular as Dropbox is, reviewers say that Google Drive (15 GB free; $2 per month for 100 GB; $10 per month for 1 TB) strongly challenges the storage giant in the cloud storage wars. Google offers far more free storage space than Dropbox (though you can get up to 18 GB free with Dropbox via referrals), and its premium subscriptions cost far less. Google Drive and Microsoft OneDrive (7 GB free; $25 per year for 50 GB) include productivity tools that allow you to edit documents, spreadsheets, slideshow presentations and other files from within your browser -- and because it's all stored online, the two services include features that let you collaborate with others to edit files together in real time. Dropbox has started offering similar collaborative functions, but there aren't many reviews of these features. There are concerns about Google Drive's privacy policies, and while Microsoft OneDrive works on Macs, its main selling point is that it's integrated into the Windows 8.1 operating system. OneDrive is so easy to use with PCs and Windows Phone -- and is so beautifully designed -- that it wins the Best Reviewed Cloud Storage for Windows.
Dropbox and Microsoft also offer business cloud storage services that focus on services for multiple users: Dropbox for Business and OneDrive for Business. Dropbox for Business costs $75 per month for five users and unlimited storage, while Microsoft OneDrive for Business is $2.50 per user per month with 25 GB per user (a 1 TB option will soon be available). But a lesser-known name comes out on top in reviews: Box for Business (Est. $15 per user per month for 1 TB) . File-syncing, collaboration, storage space and security are especially important to enterprise and small businesses and Box is strong on all levels, along with offering user controls like restricting who can edit a document.
Dropbox offers a wide variety of plans (including Dropbox Business) and a generous free account (you can earn up to 18 GB free through referrals), and it has a file-synchronization service that will please most users.
Cloud storage privacy and security
Data security is big business and, not surprisingly, has impacted cloud storage services as consumers grow more cautious about their personal information floating out in cyberspace. In light of the National Security Agency (NSA) data mining scandal -- which raised serious questions about how private our communications are -- cloud storage companies are pushing their services as safe and secure.
SpiderOak's (2 GB free; $10 per month for 100 GB) business model focuses on privacy and security; it prides itself on airtight encryption and a "Zero Knowledge" policy for customers. Instead of being stored in a cloud or in the host company's servers, your heavily encrypted files are kept on your computer. As a result, SpiderOak doesn't even have access to your file names, let alone other important information like your password. You can set up a password reminder hint, but if you forget it, you won't be able to access your account.
The program works with Windows, Mac OS X and Linux systems; free Android and iOS apps are also available. In addition to the basic plan, SpiderOak offers business options ranging from $5 to $10 per user per month.
Mega, a newer cloud storage service founded by Megaupload's Kim Dotcom, puts privacy at the forefront as well and uses a similar encryption strategy by encrypting files locally on devices, so it can't ever see the details of what you're uploading or transferring to another machine. Mega offers a generous 50 GB of free storage but doesn't come with many bells and whistles.
Experts say you should also read the terms of service and privacy policies of online storage providers before signing up with a company to ensure you agree with their terms. For example, Microsoft and Apple's privacy policies give the companies the right to scan files. While Google Drive (15 GB free; $2 per month for 100 GB; $10 per month for 1 TB) has strong encryption, it receives the biggest critiques for Google's privacy policies, which are vague about how Google can or can't use your files. Google's ad-based revenue (which pushes ads based on your personal content) is a long-standing concern of privacy mavens. In reaction to the NSA spy scandal and ad-based Internet companies, the Finnish security company F-Secure created a cloud storage company, Younited (free), on a virtual private network.
Encryption is of course critical to your file security, and experts advise using a company with multiple encryption layers as well as password protection. Many cloud storage services encrypt files during transfer but not on your device or on their servers -- although this is becoming less and less common. Some cloud storage services let you devise your own encryption key; if you're tech-savvy enough, this might be a good option.