Looking for an easy way to store all your files, but not into the idea of an external hard drive taking up space on your over-crowded – or minimalist – desk? Online storage, or "cloud" storage, is the tidy option for backing-up or storing everything from your computer, with the added convenience of your files being accessible from other devices, no matter where you are.

Out of sight, out of mind?

Most online storage services work by synchronising (syncing) your data to their servers and across online devices (tablets, laptops, smartphones etc). Generally you can create or nominate one or more hot folders on your computer, and everything in those folders will automatically sync when new content is added. You can also access the files in your hot folder via a web portal.

Just how secure online storage is depends on the service provider and what they offer. Our test of 12 popular data storage and synchronisation services found there was a range of security measures available, including various levels of encryption, protection from hackers during file transfer, and two-step verification – but not all services offered all measures. If you're concerned about storing sensitive information, make sure you understand the security features and limitations of your preferred cloud storage provider.

Video: Pros and cons of the complex world of cloud storage services

Free or paid?

Most cloud storage services provide an amount of space for free, and if you need more you start to pay. Most services we tested start you off with 5–10GB for free which is often enough for storing your most important documents, but a couple offered up to 15GB. If you're thinking of syncing high quality photos, audio and video files you'll want to consider a service with more space. You can often earn more free storage space by referring friends to the service or you can buy more space with a monthly/annual subscription.

But before you open up your wallet it's important to consider the practicalities of buying more storage. Every time your hot folder syncs you're adding to your monthly upload/download limit which can quickly cap out if you don't stay vigilant. Although 50GB of cloud storage may sound great, if your ISP limits you to 25GB per month then you're unlikely to completely use the space.

What else you need to know about cloud storage

File size limitations

On most days you're unlikely to be uploading massive files, but on the rare occasion that you need to send a few gigabytes to the cloud, you need to know whether your service puts any restrictions on file sizes. Some services don't allow files any larger than 2GB for example, whereas some may let you store anything up to 10GB in size.

Hot folders

Some services offer only one hot folder; others allow several. Some services create the hot folder that you must use; while others allow you to select an existing folder (e.g. your My Documents folder) as a hot folder.

Document viewing and editing

You might find it helpful to be able to view documents and even edit them while they're in the cloud, without first having to download them back to your computer.

Streaming media

The unlimited capacity of online storage can make it a great place to keep your movies and music – especially if the service offers media streaming to your devices. However, some services consider this to be a breach of copyright unless you own the media in question.

File versioning

Some services automatically archive older versions of files when new ones are uploaded, so you can roll back to a previous version if needed.

Folder sharing

All services allow you to share files, but only some allow you to share entire folders.

Protecting files during transfer

Check your provider uses the Secure Socket Layer (SSL) protocol, or its successor Transport Layer Security (TLS) protocol, to stop hackers from stealing files during transfer.

Protecting files when stored

There are two main methods offered to protect your files in storage:

  • Encryption: When you encrypt a file, special algorithms convert the contents into an unreadable cipher, which cannot be undone until the file detects the correct encryption key. Data encryption on cloud accounts is not a standard feature. If you want it, make sure the service uses 256-bit Advanced Encryption Standard (AES), the industry standard for server side encryption. For even greater security, User Controlled Encryption (UCE) encrypts data at the user end while it is uploaded to the cloud, and the keys to the encrypted data are held by the user rather than the company.
  • Two-step verification: When someone wants to access a file or folder, a text message or email is sent to your smartphone or other device for approval. Some services can generate one-time links for public documents, which expire once the file has been downloaded.


Protecting your files from nefarious hackers is one thing, but is it possible to ensure that your data remains completely private when it's in the cloud? Terms of service, end-user licence agreements and recent allegations of data collection by the National Security Agency (NSA) in the US suggest that your files may not be for your eyes only. Here are some points to consider:

  • All services we tested say that they have the right to access your files, but most will only do so when requested by the law.
  • Some services specifically state that employees are prohibited from viewing the content of files except for a handful who work with authorities.
  • Some services offer only a vague explanation with very few specifics, and should be treated with caution if you're serious about privacy.
  • Some services use these consumer security concerns as a selling point because their servers exist outside the jurisdiction of the NSA, in countries where unjustified data collection is not widespread. Of course this doesn't mean that your files are invulnerable to the authorities if they suspect criminal activity.
  • A couple of services we tested offer User Controlled Encryption (UCE), so even if the provider or authorities could access your files, they can't decrypt the content.

Safe servers

When you store data in the cloud you face the risk that the company's servers could fail or shut down entirely, so it's worth noting which companies duplicate your data across multiple server centres as a failsafe. Also, some services rent their space from other providers – so if the overall provider shuts down, it could affect you even if you're not a direct customer.

Five data protection tips

  1. Do not store highly sensitive or extremely important documents in the cloud if possible.
  2. Create a secure password that combines letters, numbers and symbols.
  3. Encrypt files at your end before syncing them to the cloud for improved security. The companies can only decrypt content if they own the decryption keys. 7-Zip is a free program that can encrypt files to the AES-256 bit standard. Download it from 7-zip.org.
  4. Enable two-step authentication if it's offered by the service. This can reduce the chance of unauthorised access, particularly in shared folders.
  5. If you're using a web portal on a shared computer, use private browsing mode and always remember to log out from the service.


The cloud storage services we tested ranged in price from $4.20 per 100GB to $15.10 per 100GB (after the free storage had been used).