5 Best Zero-Knowledge Cloud Storage Services
Zero-knowledge cloud storage services offer the highest level of privacy, but finding the right one can be difficult. Read on for our top five choices as we compare the best of the best in client-side encrypted cloud storage.
Written by Aleksandar Kochovski (Writer)
Reviewed by Valentina Bravo (Managing Editor)
Facts checked by Igor Kurtz (Fact-checking editor)
Last Updated:
All our content is written fully by humans; we do not publish AI writing. Learn more here.
Key Takeaways: These Are the Best Client-Side Encrypted Cloud Storage Providers
- Sync.com — The most secure all-rounder offering full zero-knowledge encryption across all files at an affordable price. Try Sync.com with its 5GB free plan, which includes client-side encryption.
- pCloud — The fastest cloud storage provider with lifetime plans, media-friendly features and an optional paid client-side encrypted folder. You can try pCloud’s 10GB free plan but it doesn’t include client-side encryption.
- Internxt — An affordable service with whole-account client-side encryption and post-quantum security. Try Internxt’s 1GB free plan, which offers client-side encryption.
- Icedrive — A sleek, easy-to-use provider with customizable sync options and an encrypted cloud storage folder. Try Icedrive’s 10GB free storage, though it doesn’t have client-side encryption.
- Tresorit — A business-focused cloud storage with top-tier privacy, zero-knowledge encryption and granular file-sharing controls. Try Tresorit’s 3GB free plan, including client-side encryption.
Facts & Expert Analysis About Cloud Storage With Client-Side Encryption:
- Zero-knowledge encryption: This form of encryption gives you full control over your encryption keys, and all data is encrypted on your device before being stored on a cloud server.
- Server location: A service’s country of incorporation and its server locations are important factors, as they dictate what data protection laws the provider must follow.
- Protection vs performance: Not all providers protect your entire storage with zero-knowledge encryption. Some apply it to one folder only, which can improve their speeds and file preview performance.
Zero-knowledge encryption is often hailed as the holy grail of privacy, and we believe this to be true. It guarantees your privacy by encrypting files while they’re still on your device before they are stored on servers, ensuring your data remains private. However, discovering the best zero-knowledge cloud storage can be difficult, and this article aims to help you find the right fit for your needs.
The services on this list all implement zero-knowledge encryption in various ways, offering different features and price points. They have more to offer than just the encryption, though, and you’ll find all of them listed in our best cloud storage article. We’ll dive into all of the specifics in detail.
We use the terms “client-side encryption” and “zero-knowledge encryption” interchangeably in this article.
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06/25/2022 Facts checked
Updated Sync.com’s pricing information.
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08/24/2022 Facts checked
Updated IDrive’s pricing information.
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05/23/2023 Facts checked
Updated to remove IDrive’s discontinued free plan and add its new free 30-day trial.
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12/07/2023 Facts checked
Updated to remove the Pro Lite plan as it is only offered in Europe.
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08/08/2024 Facts checked
Updated IDrive’s pricing information.
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08/31/2024 Facts checked
Added video reviews for cloud storage providers in the list.
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01/25/2025 Facts checked
Added new video ranking the most secure cloud storage solutions.
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03/21/2025 Facts checked
We updated the article to provide new information and features for Sync.com and pCloud.
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05/04/2025 Facts checked
Adjusted the provider list to add Internxt and Tresorit as zero-knowledge cloud providers.
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06/17/2025 Facts checked
Added updated Internxt video review for 2025.
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07/03/2025 Facts checked
Updated ranking to reflect the current status of cloud storage providers.
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07/22/2025 Facts checked
We updated our pCloud section with the provider’s latest features.
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09/24/2025 Facts checked
We rewrote this article to include new providers and to better reflect the current encryption capabilities of the services we’ve reviewed.
Cloudwards’ Choice: Sync.com
Cloudwards’ Choice: Sync.com
Sync.com is my personal favorite, as it is one of only a handful of services that protects your entire storage space with zero-knowledge encryption. It also manages to include Microsoft Office integration, though I’ve had mixed success in using it for collaboration. Even still, at prices that low, you really can’t beat it.
What Is Zero-Knowledge Encryption vs Client-Side Encryption vs End-to-End Encryption?
Zero-knowledge encryption — also called client-side encryption — refers to a method in which the user controls their own encryption key. This secret key is stored on your device, where it encrypts files before they leave that device.
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This ensures that only you, the user, can access your files — you are the only person holding the keys needed to decrypt them. There’s no need to rely on trust because the provider itself can’t access your sensitive files, nor can any malicious actors who might have infiltrated its systems.
End-to-end encryption is a closely related term that refers to any encrypted data transfer between two devices where only the sender and recipient can decrypt the data, ensuring no one can read the information. You can learn more about encryption in our encryption guide and our cloud security guide.
How to Choose the Best Zero-Knowledge Encryption Cloud Storage
When choosing the best encrypted cloud provider for your needs, in addition to zero-knowledge encryption, you should look for features that matter to you most, as well as the overall value that the service offers.
- Privacy and encryption systems: Look for a service with an ironclad policy, preferably one that doesn’t use U.S. data centers. It should obviously use zero-knowledge encryption, but some services apply this to your entire storage, while others protect only one folder.
- Productivity and collaboration features: Very rarely, a secure storage service will offer integrations with document editing suites like Microsoft Office or Google Workspace. If you need to collaborate in a private environment, this should be a top consideration for you.
- Storage space: The available storage space varies from provider to provider, with larger capacities coming at higher prices. You can also get unlimited storage with some services, such as Sync.com.
- Pricing and value: You should weigh all the features you need against the cost of the service and see if it fits your budget.
The 5 Best Zero-Knowledge Cloud Storage Services Compared
| Service: | Free Storage | Best Price | Server Locations | Client-Side Encryption | Online Collaboration | Advanced Sharing | Security |
|---|---|---|---|---|---|---|---|
 | 5GB | $4.80 per month (one-year plan) for 2TB | Canada | Microsoft Office | AES-256, TLS/SSL | ||
 | 10GB | $8.33 per month (one-year plan) for 2TB | EU, U.S.* | ** | None | AES-256, TLS/SSL | |
 | 1GB | $1.30 per month (one-year plan) for 1TB | EU | None | AES-256, TLS/SSL | ||
 | 10GB | $4.92 per month (one-year plan) for 1TB | EU, U.S. | None | Twofish, TLS/SSL | ||
 | 3GB | $19 per month (one-year plan) for 1TB | Global | None | AES-256, TLS/SSL |
**Paid add-on
Speed Comparison: Client-Side Encrypted Cloud Storage
To test speeds, we use a remote rig with a 1 Gbps connection, which we throttle down to 100 Mbps to give more realistic results for the average user. We use a 5GB test folder with a variety of file types and sizes, uploading and downloading it twice over the 100 Mbps connection and twice over the unthrottled 1 Gbps connection. Then we average the results.
| Service: | Upload* | Download* | Upload** | Download** |
|---|---|---|---|---|
| 0:09:47 | 0:11:56 | 0:09:36 | 0:10:56 |
| 0:07:06 | 0:06:52 | 0:02:06 | 0:02:33 |
| 0:08:01 | 0:09:28 | 0:07:48 | 0:09:27 |
| 0:12:12 | 0:13:00 | 0:11:50 | 0:12:37 |
| 0:07:45 | 0:07:46 | 0:07:05 | 0:02:54 |
**1 Gbps
1. Sync.com— Best Zero-Knowledge Cloud Storage Provider
Sync.com is the top provider offering client-side encryption. Unlike many similar services, it encrypts your entire storage client-side. For comparison, pCloud and Icedrive do this for only one folder. In addition, Sync.com hosts its servers in Canada, which means that your files are further protected by Canada’s privacy laws.
Apart from its strong security and privacy, Sync.com offers a great all-round feature set that includes Microsoft Office integration. This allows you to create and edit Word documents, Excel spreadsheets and PowerPoint presentations using the online version of Office, all without compromising the zero-knowledge encryption.
Sync.com Hands-On Testing
When we tested Sync.com, we found its apps to be relatively simple and easy to use. Despite its name, it doesn’t offer much in the way of file syncing options, apart from the standard sync folder where you add files to sync to the cloud. Thankfully, the latest versions offer a feature called CloudFiles that makes the files online-only by default, saving space on your device.
All that said, Sync.com isn’t perfect by any means. In our testing, we had some issues with previewing documents, and our edits were sometimes slow to fully register and sync. However, for the price and peace of mind you get, it’s easily the best balance of security and usability you’ll find.
Notes From the Lab: Sync.com Speed Test Results (5GB Folder)
| Provider: | Average Upload* | Average Download* | Average Upload** | Average Download** |
|---|---|---|---|---|
| 0:09:47 | 0:11:56 | 0:09:36 | 0:10:56 |
**1 Gbps
Speed isn’t Sync.com’s forte, but it’s not the worst performer on this list — that dubious honor goes to Icedrive. One interesting thing we gleaned from the test results is that its speeds didn’t really improve when we unthrottled the connection and let it run at full speed. This could point to older server hardware or other hardware limitations.
Notes From the Lab: Sync.com Security Analysis
including your photo backups.
| Encryption Type | Encryption Protocols |
|---|---|
| Encryption at rest | AES-256 |
| Encryption in transit | TLS/SSL |
| Client-side encryption | Yes, whole storage |
Key Security & Privacy Features:
- Encrypted sharing links
- Two-factor authentication
- HIPAA compliance possible
- GDPR compliance (EU users)
- Canadian privacy laws (PIPEDA)
- Client-side encryption for all files
- Collaboration in zero-knowledge environment
- Duplicate files across servers for data loss prevention
Sync.com’s privacy is top-notch. It not only covers all your files with zero-knowledge encryption, but it also abides by Canadian privacy laws, which are much stricter than those in countries like the U.S. Additionally, it employs redundancy measures in case a server storing your files malfunctions.
Sync.com Pricing & Value
Besides its strong security and privacy, Sync.com comes at a bargain-bin price. Its 2TB plan costs just $4.80 per month, billed yearly. It even has a relatively cheap unlimited storage plan costing just $15 per month per person (three-user minimum). Try Sync.com for yourself using its 5GB free plan, or read our full Sync.com review.
- 5GB
- 2TB
More plans
- 6TB
- per user, per month, billed annually
- 1TB
- Priced per user (3 users minimum)
- Unlimited GB
- Minimum 100 users, custom requirements, account manager, training options
2. pCloud— Fastest Cloud Storage With Client-Side Encryption
pCloud is a secure cloud service with an expansive media-oriented feature set, including an advanced music player with playlists and a Kodi integration for streaming videos. It also offers a cloud backup feature, which can help prevent data loss in case you accidentally delete your files from your device or they get infected with malware.
pCloud Hands-On Testing
Apart from its versatile feature set, pCloud also offers a variety of syncing options. This includes a sync folder, along with the option to sync any additional folder you want. It even has a virtual drive that lets you access and manage your client-side encrypted folder.
Most of pCloud’s features worked as advertised, and the virtual drive was particularly fast and responsive. The only thing we found lacking was pCloud’s own document manager, a feature available only for business users. It was slow to respond, the UI was clunky, and changes wouldn’t always save. This is why we don’t recommend using it, even if you’re on a business plan.
Notes From the Lab: pCloud Speed Test Results (5GB Folder)
| Provider: | Average Upload* | Average Download* | Average Upload** | Average Download** |
|---|---|---|---|---|
| 0:09:47 | 0:11:56 | 0:09:36 | 0:10:56 |
**1 Gbps
pCloud has the fastest speeds of any cloud storage we’ve tested. Besides its impressive performance in the 100 Mbps test, it had the largest gain from the unthrottled connection — no other service came close.
Notes From the Lab: pCloud Security Analysis
for an add-on called pCloud Encryption.
| Encryption Type | Encryption Protocols |
|---|---|
| Encryption at rest | AES-256 |
| Encryption in transit | TLS/SSL |
| Client-side encryption | Yes, single folder (paid add-on) |
Key Security & Privacy Features:
- Swiss privacy laws
- Two-factor authentication
- GDPR compliance (EU users)
- Client-side encryption (single folder, not free)
- Additional password protection for Crypto files
Although pCloud has zero-knowledge encryption, it covers only one folder — the Crypto folder (no relation to cryptcurrency). Additionally, to get access to this folder, you have to pay extra. However, even for files that are outside this folder, your privacy is still protected by Swiss and EU laws as long as you choose the EU server location.
pCloud Pricing & Value
pCloud’s base package is relatively affordable, though the cost increases with the zero-knowledge add-on. Its 2TB plan costs $8.33 per month on a yearly basis. Thankfully, it offers lifetime deals that can save you money in the long run. The encryption add-on also comes with a lifetime option. Try pCloud using its 10GB free plan, or read our pCloud review for more.
- 10GB
- 500GB
- 2TB
More plans
- 10TB
- + FREE Encryption
- 2TB
- + FREE Encryption
- 10TB
- Price per user (minimum 3)
- 1TB
- Price per user (minimum 3)
- 2TB
- Encryption for pCloud Drive
3. Internxt — Affordable Post-Quantum Encrypted Storage
Internxt is an interesting case as it’s not just a cloud storage service. A subscription gives you access to cloud storage, a virtual private network (VPN) and an antivirus, providing a full security suite.
In particular, its cloud service focuses on high security — it covers your entire storage with client-side encryption, uses post-quantum encryption and offers a backup feature for loss prevention.
Internxt Hands-On Testing
In our experience using Internxt, we found it to be fairly stripped down. While this bodes well for novice users, it doesn’t allow for much customization. Its desktop app uses a sync folder and doesn’t let you sync other folders. In addition, its mobile app doesn’t even offer the basic feature of automatically uploading photos and videos.
While stress-testing the service, we ran into issues when uploading large amounts of files. As such, we recommend that you don’t try to sync too many files at once when you first start it up, as this can lead to loss of files. The web app was also slower than we’d like, with folders and pages taking a few seconds to open.
Notes From the Lab: Internxt Speed Test Results (5GB Folder)
| Provider: | Average Upload* | Average Download* | Average Upload** | Average Download** |
|---|---|---|---|---|
| 0:09:47 | 0:11:56 | 0:09:36 | 0:10:56 |
**1 Gbps
Internxt’s speeds are average, landing in the middle of our results table. We found it somewhat concerning that its speeds didn’t improve at all over the faster connection, which could point to server limitations or throttling.
Notes From the Lab: Internxt Security Analysis
| Encryption Type | Encryption Protocols |
|---|---|
| Encryption at rest | AES-256 |
| Encryption in transit | TLS/SSL |
| Client-side encryption | Yes, whole storage |
Key Security & Privacy Features:
- Post-quantum encryption
- Two-factor authentication
- GDPR compliance for all global users
- Zero-knowledge encryption for all files
Besides zero-knowledge encryption, Internxt uses post-quantum encryption methods. Put simply, this future-proofs its security by making its encryption nearly impossible to break, even if the attacker is using a quantum computer in the future.
Internxt Pricing & Value
Internxt is surprisingly cheap, especially considering it bundles a VPN and antivirus with your cloud storage subscription. A 3TB plan costs just $2.60 per month on a yearly plan, and you can even get an Internxt lifetime plan for extra savings. Sadly, its free plan is just 1GB. Read our Internxt review for more.
- 1GB
- Storage + VPN (FR), Antivirus, Backup & More
- 1TB
- Storage + VPN (FR, DE, PL), Antivirus, Backup & More
- 3TB
More plans
- Storage + VPN (FR, DE, PL, CA, UK), Antivirus, Backup & More
- 5TB
- Storage + VPN (FR, DE, PL), Antivirus, Backup & More
- 1TB
- Storage + VPN (FR, DE, PL, CA, UK), Antivirus, Backup & More
- 2TB
4. Icedrive — Easy-to-Use Zero-Knowledge Cloud Storage
Icedrive doesn’t really stand out for its features or speed, but it does shine in one area: looks. It is one of the most beautifully designed cloud storage services — and yes, it’s also secure, offering a zero-knowledge encrypted folder. It’s among the most customizable services in terms of cloud syncing.
Icedrive Hands-On Testing
Icedrive’s apps look truly stunning, but they’re also functional. It’s one of the few services that had no issues during testing, and we encountered no bugs when syncing files. It doesn’t have a default sync folder, opting for a virtual drive instead. You can also set up custom sync pairs, with the option for one-way syncing as well, which functions like pCloud’s real-time backup.
We have to commend Icedrive for the smooth experience in all of its apps. Its mobile app was particularly impressive, with a high degree of customization for automatic media uploads, including uploading them directly to the encrypted folder.
Notes From the Lab: Icedrive Speed Test Results (5GB Folder)
| Provider: | Average Upload* | Average Download* | Average Upload** | Average Download** |
|---|---|---|---|---|
| 0:12:12 | 0:13:00 | 0:11:50 | 0:12:37 |
**1 Gbps
If there’s one downside to Icedrive, it’s speed. It was the worst performer in our 100 Mbps test. Unfortunately, things didn’t improve much over the faster 1 Gbps connection, despite our testing rig’s close proximity to its EU servers.
Notes From the Lab: Icedrive Security Analysis
use to back up your photos automatically.
| Encryption Type | Encryption Protocols |
|---|---|
| Encryption at rest | AES-256 |
| Encryption in transit | TLS/SSL |
| Client-side encryption | Yes, whole storage |
Key Security & Privacy Features:
- Two-factor authentication
- GDPR compliance (EU users)
- Less common Twofish encryption
- Client-side encryption (single folder, not free)
Icedrive has only one client-side encrypted folder; thankfully, it’s available for all paying users. It also uses the Twofish algorithm to encrypt your files, allegedly because attackers will be much less familiar with it compared to the more common AES-256.
Icedrive Pricing & Value
Icedrive is very affordable, especially if you subscribe to a long-term plan. A 1TB annual plan costs only $4.92 per month, and you can get even bigger savings if you choose an Icedrive lifetime plan. Try Icedrive using its 10GB free plan, or read our full Icedrive review for more.
- 10GB
- 1TB
- 3TB
More plans
- 5TB
- 2TB
- Additional 1TB storage for users who purchased the Lifetime Plan
- 1TB
- Additional 5TB storage for users who purchased the Lifetime Plan
- 5TB
5. Tresorit — Best Zero-Knowledge Cloud Storage for Businesses
Tresorit is a business cloud storage, which means it’s not the best for personal users, especially considering its high price tag. That said, it’s highly secure and private, and it offers granular sharing features, as well as user and document management panels.
Tresorit Hands-On Testing
Using Tresorit is relatively easy thanks to its clean and intuitive design. The desktop app installs a default sync folder, but thanks to selective sync, you can choose folders to keep online-only. You also get access to a virtual cloud drive, as well as the ability to sync any folder on your device.
Notes From the Lab: Tresorit Speed Test Results (5GB Folder)
| Provider: | Average Upload* | Average Download* | Average Upload** | Average Download** |
|---|---|---|---|---|
| 0:12:12 | 0:13:00 | 0:11:50 | 0:12:37 |
**1 Gbps
Tresorit’s speeds are generally great — only pCloud beat it in this comparison. One oddity we observed is that the downloads improved greatly in the unthrottled test, but the uploads saw only a minor improvement.
Notes From the Lab: Tresorit Security Analysis
authentication methods to safeguard your logins.
| Encryption Type | Encryption Protocols |
|---|---|
| Encryption at rest | AES-256 |
| Encryption in transit | TLS/SSL |
| Client-side encryption | Yes, whole storage |
Key Security & Privacy Features:
- Swiss privacy laws
- Two-factor authentication
- Zero-knowledge encryption for all files
- Fully GDPR compliant for all users globally
Tresorit is secure and private, not only covering all your files with zero-knowledge encryption but also complying with multiple online privacy laws. These include strict Swiss laws and the European GDPR, whose protection extends to all users, not just those residing in Europe. It also offers the possibility for HIPAA compliance, which is a testament to its airtight privacy.
Tresorit Pricing & Value
Unfortunately, Tresorit is very expensive. A 1TB plan costs $11.99 per month on a yearly basis, and it has a file size limit of 10GB as well as a file sharing limit of just 2GB. Tresorit’s free plan is just 3GB with a 500MB file size limit, and it even offers 14-day trials for its paid plans. Learn more in our full Tresorit review.
Is There a Free Zero-Knowledge Cloud Storage Provider?
Yes. In fact, three of the providers we listed have client-side encrypted free plans — Sync.com, Internxt and Tresorit — though each comes with limitations.
Why You Need Cloud Storage With Client-Side Encryption
Client-side encrypted cloud storage ensures the privacy of your files, but that’s far from the only reason to use it.
- Secure collaboration: These cloud services allow you to collaborate on files within a private environment.
- Secure file sharing: Client-side encrypted file-sharing links let you send sensitive files without worrying that they’ll be intercepted or accessed by anyone other than the intended recipient.
- Regulatory compliance: Client-side encryption is often a requirement for complying with regulations such as HIPAA, as it means that no third parties can access the stored data.
- Data breach protection: With client-side encryption, even if someone gains access to the servers of your chosen cloud storage service provider, your files will still be completely unreadable to them.
Our Methodology: How We Tested the Zero-Knowledge Encrypted Cloud Storage Providers
Our testing team runs extensive tests on all the services we review before we make any conclusions about the provider.
- Security: We use network analysis software to test if the services truly use zero-knowledge encryption, and to check where their servers are located.
- Privacy: We examine the services’ privacy policies for any suspicious wording, and we check their jurisdictions of operation. We also confirm which privacy laws and standards they follow.
- Speed: We run tests on a remote virtual machine over a controlled connection to see how the services perform over slower and faster connections.
- Performance: We stress-test the services by attempting to sync large amounts of small files and then editing some of the files. This lets us see how the services behave under extreme use cases.
Final Thoughts
Zero-knowledge cloud storage is the best choice for privacy as it ensures that only you can access your files. Our top choice is Sync.com thanks to its low cost and well-rounded feature set, including Microsoft Office integration. Get the 2TB plan for just $4.80 per month (one-year plan).
What is your favorite encrypted cloud storage service? Did it make our list? Have you used any of the services we reviewed, and if so, what was your experience with them? Please let us know in the comments below, and as always, thank you for reading.
FAQ: Best Cloud Storage With Client-Side Encryption
Zero-knowledge encryption protects your data by scrambling your files while they’re on your device, which means that only you can decrypt them.
Zero-knowledge cloud storage is any cloud storage that uses zero-knowledge encryption to protect your files.
No, OneDrive is not a zero-knowledge service as it encrypts files on its own servers and holds your encryption keys.