When it comes to cloud security for file hosting, private, end-to-end encryption is kind of the gold standard. While actually a hijacked term in cryptography, today it’s common to call this this type of encryption “zero-knowledge.”

Zero-knowledge encryption means only you have control of your cloud encryption keys, so only you can ever decrypt your files into plain text. That means no sketchy government surveillance, no using your private photos for targeted marketing and less chance of a breach compromising your identity.

However, while any zero knowledge is good, some implementations are better than others. During this roundup, we’ll unveil our picks for the best zero-knowledge cloud services available today. Headed by what may actually be the overall best cloud storage service, Sync.com, this list will help keep your private affairs exactly that.  

Starts from $ 408 per month for 500 GB
Free plan available

Best Zero-Knowledge Cloud Services of 2019

cloudwards rating
$ per month
top features
Starts from $ 408 per month for 500 GB
Free plan available

What Makes the Best Zero-Knowledge Cloud Service

If you’re not quite sure what the difference between managed and private encryption is, we have a complete article on the basics of zero knowledge that will set you right.

We also have an online privacy guide focused on the best practices you can follow to keep you safe on the web, of which zero-knowledge encryption, along with finding a trusty VPN, plays a big part.

Finding the best zero-knowledge provider starts, of course, with making sure its a zero-knowledge provider. That leaves out some popular favorites, including Dropbox, Google Drive and OneDrive, unless you want to take your encryption DIY with a service like Boxcryptor.

After that, there are a number of things we considered. Since those who prefer zero-knowledge encryption tend to be focused on security, we looked for cloud services that did other things to compliment that calling, like two-factor authentication and passwords for shared file links.

We also considered elements of good cloud services in general, like value, sync capabilities and ease of use. So, basically all the same criteria that go into putting together our cloud storage reviews.

Now that the explanations are out of the way, let’s get to the important stuff: the winners.  

Best Zero Knowledge Cloud Service: Sync.com

Sync.com has been one of our favorite cloud storage services for years now, and that’s an opinion largely propelled by the service’s unmatched approach to security.   First of all, you’re not charged extra for zero-knowledge encryption like your are with our second pick on this list, pCloud.

Share a file with Sync.com

On top of that, Sync.com is one of the few cloud storage services to maintain zero-knowledge encryption even for shared files.

Besides that, Sync.com also has an option for two-factor authentication and incorporates file sharing features to bolster security like passwords, expiry dates and download limits for file links. You can read more about Sync.com’s approach to security in our full Sync.com review.

It’s about as ironclad as cloud storage gets, with maybe only Tresorit coming close to matching it.

Other Reasons Why We Like Sync.com

On top of being the most secure cloud storage solution we’ve ever used, Sync.com also provides some of the best value. You can get a free 5GB account and add to that with an unlimited referral program, or you can just secure 2TB of space for about $8 a month. That’s easily one of the best deals in cloud storage.


  • 2TB of storage for cheap
  • Very secure file sharing
  • Zero-knowledge included


  • No file previews
  • No media streaming
  • No Linux
Starts from $ 408 per month for 500 GB
Free plan available


Sync.com and our second-place finisher, pCloud, have been playing tug-of-war with our heartstrings for a while now. You can read our latest thoughts on that subject in our Sync.com vs pCloud head-to-head article.

We ranked pCloud second on this list mostly because zero-knowledge encryption costs extra with pCloud. You’ll need to purchase pCloud Crypto, which right now goes for $4.99 a month, though you’ll get a 20 percent discount paying a year in advance.

On top of that, files protected with pCloud Crypto can’t be shared, so it’s not quite as flexible as Sync.com. Files have to be placed in a separate Crypto folder, which is separate from the regular pCloud sync folder.

However, by not extending zero-knowledge encryption to all files, pCloud is able to do some things Sync.com can’t, like stream music and preview images. It’s one of the best cloud storage for photos and media, which for some should make pCloud a better pick than Sync.com.

Other Reasons Why We Like pCloud

Aside from being almost as secure and more versatile than Sync.com, pCloud is also just about as cheap. With a one-year subscription, you can get the same deal, 2TB for $8 a month, though remember you’ll have to pay extra for Crypto.

Overall, pCloud also has one of the nicer web GUIs we’ve seen, and is one of the few cloud storage services with a client for Linux (see our picks on best cloud storage for Linux).


  • Good value on storage
  • Good for media streaming
  • Good for photos


  • Zero-knowledge costs extra
  • No two-factor authentication
Starts from $ 399 per month for 500 GB
Free plan available Save 20 %

SpiderOak ONE

Unlike our first two picks, our third selection isn’t a cloud storage service, its actually an online backup service. We have a full article on the differences between storage and backup, but basically it means that SpiderOak ONE is designed more for disaster recovery than complementing your hard-drive space.

However, SpiderOak is one of those services that blurs the line between storage and backup a bit. As you can read about in our SpiderOak ONE review, any files in your SpiderOak backup plan can also be synced and shared.

As an online backup service, SpiderOak ONE is very good, with support for backing up unlimited computers, continuous backup and unlimited file versioning. Zero-knowledge encryption comes included in the subscription price with SpiderOak, although that price is a bit more expensive than some of the alternatives in our best online backup guide.

Other Reasons Why We Like SpiderOak ONE

SpiderOak ONE takes a more structured approach to file sharing than most cloud services. It uses something called ShareRooms, which are kind of like password-protected shared folders, but much fancier. As with pCloud, be careful here: shared files lose their zero-knowledge protection.

While more expensive than online backup solutions like Backblaze (read our Backblaze review), SpiderOak is also more versatile thanks to its cloud features. However, that means it can be a bit trickier to use, so have a look at our how-to-use SpiderOak ONE guide if you’re stuck in a web of confusion.


  • Zero-knowledge included
  • Good backup features
  • Sync & file sharing included


  • A bit expensive
  • More learning curve
Starts from $ 575 per month for 150 GB
Free plan available


There’s no question that Tresorit is one of the most secure cloud storage services available. Whether Tresorit is actually better for privacy than Sync.com, you can read about in our Sync.com vs Tresorit comparison. Zero-knowledge encryption is the key feature of Tresorit security.

Not only is it included by default, zero-knowledge encryption is extended to shared files. That fact, along with password protection, expiry dates and download limits for file links at least puts Tresorit alongside Sync.com when it comes to secure file sharing.

Two-factor authentication is also an option, unlike with pCloud and SpiderOak ONE.

What hurts Tresorit on this list, and keeps it from vying for the top spot, is that it’s much more expensive than Sync.com, pCloud and even SpiderOak. You can read about its unfortunately high cost of service in our complete Tresorit review.

Other Reasons Why We Like Tresorit 

Aside from being really secure, about the only thing we can say on Tresorit’s behalf is that at least has a Linux client, which puts it in rare company. While Tresorit is quite a bit more expensive than pCloud, we could easily argue that it’s the most privacy-focused cloud storage tool for Linux.  

Sadly, to figure that out for yourself, there’s not even a free Tresorit plan like you get with just about every other cloud provider. The best you can do is try the service out with a 14-day free trial before committing.  


  • Zero-knowledge file shares
  • Two-factor authentication
  • Linux client


  • Expensive
  • No free offer
  • No file previews
Starts from $ 1042 per month for 200 GB
Free plan available Save 17 %


MEGA’s inclusion in this list is more an indication of just how small the fraternity of zero-knowledge cloud services is rather than serious recommendation. MEGA’s got too many blemishes for that, although 50GB of free cloud storage might encourage a pretty big blindspot.


Zero-knowledge encryption is free, too, and extends to file sharing. The actual file-sharing process with MEGA, however, feels a bit clunkier than what you’ll get with most other cloud storage services. We have screenshots in our MEGA review.

MEGA also doesn’t offer any file versioning, which is rare. We’ve had some problems syncing large files, too, though smaller files copy just fine. Finally, if you ever want more than 50GB of storage, MEGA becomes expensive

Other Reasons Why We Like MEGA

As with Tresorit, there’s not much more to say. We could talk some more about why we don’t like MEGA. Or, just read this article about why Sync is so much better than MEGA.


  • Free 50GB of storage
  • Zero-knowledge file shares


  • No two-factor authentication
  • No file versioning
  • Sync problems
Starts from $ 569 per month for 200 GB
Free plan available


Zero-knowledge security almost always means the service that includes it is probably going to be more secure than Dropbox. Whether or not they’re actually capable Dropbox alternatives depends on what more they do, though.

While we like Sync.com because of its all-around great security and its value, those looking for a bit more flexibility might be better off with pCloud or SpiderOak ONE. If you’re looking for the most secure cloud storage for Linux, however, that crown might go to Tresorit over pCloud, and certainly over MEGA.

Use the comment section below to let us know your own thoughts on private, end-to-end encryption and the best cloud services to use it. Thanks for reading.

Starts from $ 408 per month for 500 GB
Free plan available

7 thoughts on “Best Zero-Knowledge Cloud Services 2019”

  1. How do I protect against a complete crash on, say, Computer A; i.e., no computer no longer works. The no longer available Crashplan would allow me to restore the Computer A backup to a new computer. Is that possible with SpiderOne or Carbonite?

  2. For future reviews of cloud services, especially backup and storage, please include information from the companies on whether they have multiple data centers in disparate regions of the country. This is critical so that, if the entire Northwest suffers a power outage, for instance, users will be able to access their data if there is also a data center in Chicago. The company ‘Sync’ provided the following statement to me in response to my query. Other companies stated that they have only a SINGLE data center. Sync: “Data is replicated across multiple datacenter locations. In the event of catastrophic hardware failure, we can failover to a mirrored dataset at an entirely different location. In a real world scenario, data replication across multiple datacenter locations allows us to perform system and network maintenance without any measurable downtime for you.”

  3. My brother, using Mac, and I, far away, using Linux, are working on a project in Open Office where we want to share files via cloud storage while retaining zero-knowledge status throughout. Do any of the services you recommend provide this?

  4. Cloudwards.net

    pCloud has both Linux and Mac clients and would retain zero-knowledge throughout so long as you add the Crypto add-on. MEGA does, too, as does Tresorit. However, pCloud is the best of the three.

  5. SpiderOak currently does not offer MFA except for users who had it before bit was canceled.

  6. Hi, pcloud’s website says they offer two-factor authentication, but I keep reading in multiple locations that they do have it. You just have to look up pcloud’s Q&A sections under general (question #66) is pretty clear. If I am correct, it would be good to update the article. Could be a new feature that they added this year (2019).

    Thanks again,

Leave a Reply
Your email address will not be published. Required fields are marked *

Also interesting
Best Free Online BackupBest Free Online Backup for 2019: Peace of Mind on the Cheap
How to Use a Gantt ChartHow to Use a Gantt Chart: A Beginner’s Guide for 2019
Dutch IP AddressHow to Get a Dutch IP Address in 2019: Rerouting to Rotterdam
Best VPN for the NetherlandsBest VPN for the Netherlands in 2019: Going Dutch
Most popular on Cloudwards
Free Cloud Storage in 2019: Top Five Providers with Large Free Service Plans
Best of The Big Three: Dropbox vs Google Drive vs Onedrive
How to Beat the Netflix VPN Ban
How to Unblock YouTube: Video Streaming for Everyone