Best Zero-Knowledge Cloud Storage of 2021: Protection From Prying Eyes

Choosing a cloud storage provider that offers zero-knowledge encryption is the best way to ensure that your data remains private. This list of the best zero-knowledge cloud storage will help you pick the right one.

Aleksandar KochovskiBranko Vlajin
By Aleksandar Kochovski (Editor) & Branko Vlajin (Writer)
— Last Updated: 2021-07-06T21:27:40+00:00 Facts checked by Andrea Babic

Data has become a currency in the modern world, and everyone is out to get your personal information. That’s the case whether it’s your internet service provider (ISP) tracking your online activity, a Silicon Valley giant farming your search information or a nosy government agency looking for suspicious activities. Zero-knowledge cloud storage can help keep your sensitive files away from prying eyes.

Zero-knowledge encryption is a way of encrypting your data where only you have access to your encryption key, so no one else can decode it. When it comes to storing files online, zero-knowledge cloud storage is the only way to keep your data 100 percent safe. It is even more secure than your external hard drive (they tend to break down or get lost).

Storing data safely is crucial nowadays, which is why we rounded up the best zero-knowledge cloud services to help you make the right choice. Our top choice is Sync.com, offering top-notch security at a very competitive price. With good privacy laws in place and adequate zero-knowledge protection, all the cloud storage services on this list will help keep your files safe.

  • Zero-knowledge encryption scrambles your data using an encryption key that only you know. It guarantees that no one but you can see your data in its unscrambled form.

  • Zero-knowledge cloud storage encrypts all of your files client-side, which means that not even its employees can access your files.

  • If you need secure cloud storage, you can’t go wrong with Sync.com. It offers zero-knowledge encryption even for its free users and it’s compliant with European and Canadian privacy laws. It’s even certified to hold sensitive medical data, too.

What Makes the Best Zero-Knowledge Cloud Storage

Although airtight security is a must for every service on this list, the best zero-knowledge cloud providers offer more than just secure cloud storage privacy. Some services excel in some areas but are a letdown in others. The best service strikes a balance between security, features and price. Here are our top five choices:

  1. Sync.com — The best cloud storage service overall
  2. pCloud — Blazing fast and super secure cloud storage
  3. Icedrive —  A newcomer showing a lot of promise
  4. MEGA.nz — Secure and private cloud storage with a generous free plan
  5. IDrive — Hybrid cloud storage solution with cheap storage

Obviously, the cloud storage service needs to offer zero-knowledge protection. We’ll make sure that it’s strong and doesn’t have loopholes that the business might use to invade your privacy.

Strong cloud security is also a must. It includes features such as encrypted file sharing, the SSL/TLS protocol to protect your files in transit and more. Two-factor authentication, which protects your account, is important, too.

It’s best to have plans that provide more storage for cheap. A spacious free plan is never a bad thing, either. If you’re looking for a great deal, check out our picks for the best deals in cloud storage.

An enjoyable and straightforward user experience is also a must because it would make your interaction with the cloud storage service much more pleasant. An intuitive and easy-to-use interface is an integral part of the overall experience. Plus, clients should work on the most popular operating systems and run on desktop, web and mobile.

How fast you can transfer your files will depend on your ISP, the cloud storage service and how close you are to its servers. The closer you are to the service, the better your connection speed will be.

1. Sync.com

Sync.com best zero-knowledge cloud storage
Sync.com offers excellent security at an affordable price.

More details about Sync.com:

  • Pricing: $8 per month for 2TB of storage
  • Provider website: Sync.com

Pros:

  • Strong security
  • Great value
  • Good ease of use

Cons:

  • Slow
  • No monthly plans

Sync.com was founded in 2011 in Toronto, and its dedication to strong user security and privacy helped it top this list. Because it’s based in Canada, you get the benefit of Canadian privacy laws.

It scrambles your files using AES 256-bit encryption and uses the TLS protocol to protect files in transit to its servers from man-in-the-middle attacks (Sync.com is our best encrypted cloud storage provider, too).

The service is zero-knowledge-compliant. Plus, it provides two-factor authentication to help protect your password from hackers, but you should make a strong password regardless.

Sync.com’s data centers use RAID architecture to prevent server failures from leading to data loss and are SOC 1-certified. Thanks to those features, Sync.com is at the top of our most secure cloud storage list.

Sync.com Pricing

Before deciding to subscribe, you can use Sync.com’s free plan, which provides 5GB of storage. It’s not much, but it helps it make our best free cloud storage roundup. Still, it’s enough to see if Sync.com works for you. Completing a few simple steps will get you 1GB of additional storage. You can also add 1GB per referral up to 20GB.

If you’re looking for a great cloud storage deal, look no further than Sync.com’s paid plans. It offers 2TB of storage for only $8 per month, and its other pricing plans are a steal, too.

The only caveat with its pricing plans is that they’re only available as a yearly subscription. That means, if you’re planning on using Sync.com for just a short period, you’ll still have to pay for the whole year. However, if there’s any service worth the commitment, it’s definitely Sync.com.

Sync.com’s Ease of Use & Speeds

Sync.com’s desktop client is easy to use. You can access it via the taskbar icon. It works on Windows and macOS, but not Linux. If you want Linux support, read our best cloud storage for Linux comparison.

For us, Sync.com’s transfer speeds were slower than average. However, the fact that its servers are in Ontario, Canada, and we were in North Macedonia when we performed our speed tests likely made a difference. You should expect to have faster speeds if you’re closer to its servers.

If transferring uses too much of your system resources, you can throttle the sync process. There’s also an option to limit monthly uploads and downloads if you have a limited data plan.

Sync.com doesn’t use block-level sync. That’s normal, though, because block-level sync and zero-knowledge encryption don’t work well together.

Sync.com does a great job of ensuring its users’ privacy and security, plus it has cheap subscription plans and is easy to use, all of which helps it top this list. Check out our full Sync.com review for more details.

2. pCloud

pCloud privacy cloud storage
pCloud is easy to use and secure if you pay extra for private encryption.

More details about pCloud: 

  • Pricing: $9.99 per month for 2TB of storage
  • Provider website: pcloud.com

Pros:

  • Excellent value
  • Good ease of use

Cons:

  • Private encryption is a paid add-on

pCloud is a Switzerland-based business with servers located in both the U.S. and Europe. If you choose a European location to store your data, you’ll be protected by some of the best privacy laws in the world, including the EU’s General Data Protection Regulation (or GDPR for short). It provides zero-knowledge encryption, although you need to pay extra to get it.

pCloud calls its private encryption “pCloud Crypto,” and you need to pay $4.99 a month to use it. We suggest you get it, as the service is less secure without it. Plus, we’ve heard from readers that pCloud will go through your files to make sure nothing violates its terms and conditions if you don’t use Crypto (read more in our pCloud Crypto piece).

As a testament to its security, pCloud hosted a pCloud Crypto hacking challenge, but nobody was able to complete it.

Besides private encryption, pCloud uses the TLS/SSL protocol to protect files during transfer and AES 256-bit encryption to protect them at rest. When files reach one of its data centers, the service generates and distributes five copies to at least three servers. The data centers are secured and monitored 24/7.

pCloud also uses two-factor authentication to protect your account if someone steals your credentials.

pCloud Pricing

Before subscribing, you can use the free plan, which gives you up to 10GB of storage, but you have to unlock some of that storage by completing simple actions, such as downloading its mobile app. Plus, every friend you refer gets you 1GB of additional space up to 20GB. Thanks to that, it’s at the top of our best free cloud storage list.

pCloud has only two personal plans, and if you subscribe annually, the pricing is pretty similar to Sync.com. Its Premium Plus plan offers 2TB of storage for $9.99 per month, but you can get it for only $7.99 if you pay for the year in advance.

If you think pCloud is great and you want to use it for a long time, you can buy a pCloud lifetime license, which will save you a lot of money in the long run.

pCloud Clients & Mobile App

Using the desktop client is enjoyable and easy. You can access it with the system tray icon or the pCloud drive in your system files manager. The interface is somewhat drab, but it’s clear and intuitive. The client is available for Windows, macOS and Linux.

If you’re on a different computer and need to access your files, you can use the web interface. It’s fast, has more features and offers a fluid experience. However, it’s not great for transferring large files, so you should use the desktop client for that (read our how to use pCloud Transfer guide).

The mobile app is also easy to use. You can use it to upload photos automatically and to play audio and video files. It’s available for Android and iOS.

pCloud performed much better in our speed tests than Sync.com. Its transfer speeds topped our speed test chart, along with Icedrive, a service we’ll talk about later in this article. Plus, you can limit speeds manually if pCloud takes too much of your bandwidth.

You should know that pCloud charges extra for zero-knowledge encryption, which is the main reason we placed it behind Sync.com. For an in-depth look at pCloud, read our pCloud review.

3. Icedrive

Icedrive new secure cloud storage
Icedrive is a new cloud service dedicated to user privacy.

More details about Icedrive: 

  • Pricing: $4.99 per month for 1TB of storage
  • Provider website: icedrive.net

Pros:

  • Affordable pricing
  • Blazing fast
  • Beautiful design

Cons:

  • Lacks advanced features

Next up is UK-based Icedrive at number three on our roundup. A relatively new service, it was founded in Cardiff in early 2019. However, with its private encryption, affordable pricing and generous free plan, it stands its ground with the rest of the services on this list.

Although the UK has a bit of a dodgy reputation regarding privacy laws (the 2016 Snoopers’ Charter gave the UK government sweeping surveillance powers), Icedrive is a zero-knowledge service devoted to user privacy. It doesn’t track your data any more than it has to, and if you keep your files encrypted, no government regulation can compromise your privacy.

Icedrive’s Security & Pricing

When it comes to encryption, Icedrive differentiates itself by using the Twofish encryption protocol to protect your files at rest, rather than the industry-standard AES. Although Twofish is more secure on paper, the difference in real-world usage is nonexistent, as both protocols are virtually uncrackable. The TLS protocol keeps your files safe while in transit.

Icedrive implements zero-knowledge encryption similarly to pCloud — there’s a separate “encrypted” folder where the files you upload are kept private. The good news is that this comes at no extra charge, although free accounts don’t have access to this folder.

Speaking of free accounts, Icedrive offers one of the best free plans, with a roomy 10GB of storage, no questions asked. The pricing for its paid plans is the real kicker here, though. The Pro plan gives you 1TB of storage for only $4.99 per month — pCloud charges the same for half the storage while Sync.com only offers 200GB for the same price.

Just like the previous providers, a yearly subscription will lower the prices even further. There are also lifetime subscriptions for users who are ready to stick with Icedrive for the long haul.

Icedrive’s Slick Interface

Icedrive has one of the most gorgeous user interfaces for a cloud storage service, with blue and green accents across a clean white design, echoing its icy name. You can access Icedrive on almost any device imaginable, as its desktop app supports Windows, macOS and Linux, plus it has mobile apps for Android and iOS.

It’s easy to get around Icedrive’s website, with a highlight being the use of an actual right-click menu, which very few web interfaces have. Unlike the other services on this list (and indeed most cloud services nowadays), it has a full-featured desktop app, with the same functionality as the Icedrive website.

As we briefly mentioned, Icedrive has some of the best speeds we’ve ever tested. However, bear in mind that with any other cloud service, your transfer speeds will depend on how close you are to its UK servers.

There’s still room for Icedrive to improve, though. It’s an excellent service already and holds its own against the other cloud services on this list, but Icedrive’s roadmap reveals much more to come in the future. Read our full Icedrive review for more details.

4. MEGA

MEGA anonymous cloud storage
MEGA carries a pirate’s legacy, but it’s secure and private nonetheless.
  • Pricing: 20GB free, $11.80 per month for 2TB of storage
  • Provider website: mega.io

Pros:

  • Large free plan
  • Great user experience

Cons:

  • Slow
  • Speeds can vary
  • Prices could be better

MEGA was launched in 2013 by Kim Dotcom, and it’s one of the most controversial cloud storage companies (as far as cloud controversies go, at least). It has strong security that features zero-knowledge encryption (although our pCloud vs MEGA comparison shows MEGA has better privacy).

The level of encryption at rest is AES 128-bit, which isn’t as strong as AES 256-bit. Although as with the Twofish vs AES comparison previously, 128-bit encryption is still practically uncrackable. It also uses the TLS protocol to protect data during transfer and offers two-factor authentication, too.

MEGA Pricing and Free Plan

MEGA has four plans, but they don’t offer quite as much value as Icedrive, or even pCloud and Sync.com. The Pro Lite plan is $5.89 per month (4.99 euros) and gives you just 400GB of storage space. For 2TB of storage space, you have to subscribe to the Pro I plan, which is $11.80 per month (9.99 euros).

It offers two high-capacity plans as well. The Pro II plan comes with 8TB of storage at $23.61 per month (19.99 euros), and the Pro III plan offers a mighty 16TB of storage for $35.43 (29.99 euros) per month. All of these plans are cheaper if you pay per year.

The free plan comes with an entire 20GB of storage. Installing MEGA.io’s apps and verifying your account (via your email address, etc.) will net you extra storage, which lasts for 365 days.

MEGA’s Clients & Speeds

MEGA’s desktop client is attractive, clear and won’t leave you scratching your head. It works on Windows, macOS and Linux.

The web interface is user-friendly and straightforward, too. It has one of the best drag-and-drop features because you can drop your files practically anywhere.

You won’t have issues with mobile apps, either. It’s available for Android and iOS. The main part of the screen lets you access your files while the bottom menu lets you access chat and the camera, upload and view shared folders and your offline files. You can also set the app to upload your photos and videos automatically.

MEGA keeps its servers in Europe, Canada and New Zealand. That didn’t help us achieve the speeds we expected, though. It was slower than average for us. Plus, there are a lot of comments on our MEGA review complaining about slow speeds.

5. IDrive

zero knowledge storage idrive
Despite not being a dedicated cloud storage service, IDrive makes it onto this list.

More details about IDrive: 

  • Pricing: 5GB for free, 5TB for $69.50 per year
  • Provider website: www.idrive.com

Pros:

  • Reasonable prices
  • Great security & privacy
  • Full of features

Cons:

  • Primarily a backup service
  • Slow

Rounding out our list is IDrive. Although traditionally a backup service, IDrive comes with several features more common in cloud storage providers — like file sync and share. This, combined with its excellent security and privacy (ensured by zero-knowledge encryption), earns IDrive a spot on this list, though its lacklustre speed keeps it from a higher spot.

Besides the aforementioned cloud storage functionality, IDrive packs almost any kind of backup feature you can imagine into an easy-to-use and aesthetically pleasing package.

Recover Your Data Physically With IDrive

Like some other backup services (but not cloud storage providers), IDrive offers courier backup and recovery. In short, this means that you can request a physical hard drive from the company, which you can then upload your data to (or download it from) in order to get around bandwidth issues when backing up and restoring files.

zero knowledge storage idrive cta
IDrive’s price makes it great value for the money when compared to other services.

IDrive has some of the most reasonable prices in the backup space. Although it doesn’t offer unlimited storage like Backblaze (read our Backblaze review), you can get 5GB for free or choose between two paid plans that give you 5TB and 10TB of storage for $69.50 and $99.50 per year, respectively.

Although IDrive focuses on providing automated backups, the inclusion of file sync and share makes it a very valid alternative to traditional cloud storage. The inclusion of zero-knowledge encryption earns it a spot on this list, but if you want to learn more you can check out our full IDrive review for all the details.

Zero-Knowledge Cloud Backup

If you’d rather backup your files and need a service to help you do that, you should look no further than IDrive, Acronis True Image and SpiderOak One Backup. They’re at the top of our best online backup comparison list.

IDrive is our top pick, though, thanks to its competitive pricing, strong security and the ability to backup unlimited external devices. Acronis isn’t far behind, featuring built-in ransomware protection. Finally, you can safely backup your files using SpiderOak One with a blessing from none other than Edward Snowden.

What Is Zero-Knowledge Encryption?

Zero-knowledge is an alternative name for private, end-to-end encryption. Private means that nobody but you can read your files. That’s because encryption happens on your local device before the files transfer to the cloud. Since you use a password that only you know for encryption, no one but you can decrypt the files after transfer. That’s the “end-to-end” part.

It ensures your privacy because a zero-knowledge service can’t supply your unencrypted data to an authoritarian government, or even worse, a targeted marketing agency. That said, if you forget your password, the service won’t be able to reset it for you. To avoid that, you should use one of the best password managers to store your password.

Why Use Zero-Knowledge Cloud Storage

Laws, projects and regulations around the world are turning privacy into a luxury. Chief among the countries that implement such laws is the U.S. Uncle Sam has the PRISM project, the USA Patriot Act and the CLOUD Act. The U.S. National Security Agency doesn’t mind making use of those laws, so having the best zero-knowledge cloud storage to protect your files is paramount.

That said, other countries aren’t far behind. Some EU countries sometimes act without regard to your privacy (looking at you, Netherlands). The French have their own spying project, and the UK passed the Investigatory Powers Act, which is even more frightening than its U.S. counterparts. And that’s not even mentioning outright dictatorships with government-regulated internet.

If a cloud service isn’t zero-knowledge, you can still stay safe by using an encryption service, such as Boxcryptor (read our Boxcryptor review for more information). With your files encrypted by a third-party, you can even use big-name (and little-privacy) cloud providers like Google Drive, OneDrive and Dropbox.

Final Thoughts

When it comes to protecting your privacy, zero-knowledge encryption is your strongest ally, unlike an encrypted external hard drive. All the services on our list have it, but they differ in other categories. Sync.com takes the top spot, but the services we chose all have strong security, so you can’t make a wrong choice.

What do you think about our picks? Did we miss a service? Which cloud service do you use to protect your privacy? Check out our best VPN services for a better privacy overview and leave your response in the comments below. Thank you for reading.