Proton Drive is the best overall choice for zero-knowledge cloud storage: Swiss-based, end-to-end client-side encryption and integrated privacy tools. Use Tresorit for business/compliance-grade sharing; pick MEGA if you need a generous free tier.
2TresoritBest fit for teams needing compliance-focused, high-security collaboration where keys are generated on-device and the provider cannot read files; expects higher cost for enterprise features.73%
3Proton DriveBest overall for privacy-conscious users who want Swiss-based, end-to-end client-side encryption and integration with other privacy services; tradeoff is smaller free tier compared with MEGA.71%
If your priority is that the cloud storage provider cannot access your encryption keys or read your files, look for a service with zero-knowledge, end-to-end encryption (also called client-side encryption).
My top recommendation is Proton Drive for most personal users. Two other strong options are Sync.com for straightforward file syncing and Tresorit for advanced business security. Their published security descriptions say the provider cannot read your encrypted files.
End-to-end encryption is enabled by default for files, and Proton says even it cannot read your stored content. Its apps are open source, and its security has been independently audited.
Best for: Personal files, photos, documents and backups.
Free plan: 5 GB.
Website:
2. Sync.com
(Best for file syncing)
Files are encrypted before leaving your device, and Sync says it does not possess the keys needed to decrypt them. It offers file sharing, synchronization and recovery features.
Best for: Replacing conventional cloud storage for everyday file management.
Free plan: 5 GB; paid plans offer more storage.
Website:
3. Tresorit
Built around zero-knowledge encryption, with encrypted file sharing, device synchronization and business-oriented security controls. Tresorit states that it cannot access your files or encryption keys.
Best for: Confidential work documents, client files and business collaboration.
Free option: A trial is available on eligible plans.
Zero-knowledge encryption protects your files from the storage provider, but you still need to protect your account and recovery credentials.
Use a strong, unique password and enable two-factor authentication.
Store recovery information somewhere safe.
Understand that losing access to the necessary keys or recovery method can mean losing your files permanently.
If you want even less dependence on a provider's software, consider Cryptomator. It encrypts files locally before they are uploaded to a compatible cloud service, giving you another layer of control.
Let me narrow it down
What matters most to you?
1. What will you store?
Personal files and photos
Computer backups
Sensitive or confidential documents
Business files and team collaboration
2. How much storage do you need?
Under 100 GB
1–2 TB
5 TB or more
Unlimited or lifetime storage
3. What's your budget?
Free
Under $10/month
$10–$20/month
Price is secondary to security
4. How strict is your key requirement?
The provider must never hold my decryption keys
I prefer open-source software and independently verifiable encryption
I want to manage encryption keys myself, separately from the provider
Cryptomator (Alternative Approach): If you already use a mainstream provider like Google Drive, OneDrive, or Dropbox but don't trust them with your keys, Cryptomator acts as a free, open-source client-side encryption layer that encrypts your files before they sync to any cloud.[](https://mdanassaif.medium.com/best-zero-knowledge-cloud-storage-in-2026-18fdadabaeed)
Note: Because these providers operate on a strict zero-knowledge architecture, losing your master password or recovery phrase means permanent data loss —the provider cannot reset your password or recover your files for you. [](https://www.bestbackupreviews.com/guides/best-encrypted-cloud-storage/)
To help narrow down the best choice, tell me:
How much storage space do you need?
Do you prefer a subscription model or a lifetime plan?
Are you looking for desktop/mobile syncing or just browser-based backups?
If your main requirement is that the cloud storage provider must never have access to your decryption keys, look for a service with true zero-knowledge, end-to-end encryption (E2EE). That means your files are encrypted on your device before upload, and the provider stores only encrypted data—not a usable key to read your files.
My top recommendations are Proton Drive for personal use and Tresorit for business or sensitive documents. Both explicitly document zero-knowledge encryption.
Best cloud storage providers for zero-knowledge encryption
1. Proton Drive
(Best overall for personal use)
Files and filenames are protected by end-to-end encryption. Proton says it cannot read your files, and its apps are open source, allowing independent inspection.
Best for: documents, photos, personal backups and everyday file sharing.
Key consideration: account recovery and key management still matter; don't assume the provider can recover every lost encryption secret.
Website:
2. Tresorit
(Best for business)
Tresorit encrypts files on your device and says encryption keys remain under user control, not accessible to its servers. It also emphasizes secure collaboration and business compliance.
Best for: confidential business files, client documents and team collaboration.
Key consideration: compare plan pricing and administrative features before committing.
Website:
3. Sync.com
A strong alternative to compare if you want private cloud storage with file synchronization and sharing. Its zero-knowledge model is designed to prevent the provider from reading file contents.
Best for: cloud backup, file sharing and everyday storage.
Key consideration: check recovery, sharing and device-support details against your workflow.
Website:
What to check before choosing
Security requirement
What to look for
Provider cannot decrypt files
End-to-end encryption by default
Provider does not hold your keys
Keys generated and used on your device
Filenames are private too
Encrypted filenames and folder metadata
Protection against account takeover
Two-factor authentication or security keys
You can recover your files
Documented recovery process that doesn't give the provider decryption access
One important caution: zero-knowledge encryption does not necessarily hide all metadata, such as access times or account details. Also, losing your recovery information can mean permanently losing access to your files.
My recommendation: Start with Proton Drive if you're an individual who wants strong privacy without having to manage encryption manually. Choose Tresorit if you need more business-oriented controls.
To narrow this down, how much storage do you need?
Top cloud storage providers operating on a strict zero-knowledge architecture include:
Proton Drive — Uses end-to-end and zero-access encryption automatically in the background. Files, folder structures, and metadata are encrypted on your device using keys derived from your password, meaning Proton cannot read your data or recover your files if you lose your credentials.[](https://proton.me/drive/security)
Filen — A completely open-source, zero-knowledge cloud storage provider. Everything is client-side encrypted, and because the source code is publicly verifiable, you don't have to rely purely on the company's marketing claims regarding their lack of key access.[](https://mdanassaif.medium.com/best-zero-knowledge-cloud-storage-in-2026-18fdadabaeed)
If you want true zero-knowledge cloud storage—meaning the provider encrypts files before upload (or in a way where only your device can decrypt them) and the company never has your encryption keys—look for these features:
Client-side encryption (encryption happens on your device)
No key escrow (the provider does not keep a copy of your keys)
End-to-end encryption
Recovery keys you control (because the provider cannot reset your password or recover your files)
Ideally: open-source clients or independent audits
Some providers worth considering:
Provider
Zero-knowledge model
Good for
Proton /
End-to-end encrypted storage where Proton states it cannot access your files or keys
General personal cloud storage, replacing Google Drive/Dropbox
Tresorit /
Zero-knowledge encryption with keys controlled by users
Business files and sensitive documents
Sync.com /
Privacy-focused cloud storage with end-to-end encryption
Simple Dropbox-style storage
MEGA /
Client-side encryption model where users control account keys
Large storage amounts and sharing
LucidLink /
Zero-knowledge security with customer-controlled encryption keys
Teams needing high-performance cloud file access
My shortlist by use case
Best everyday personal replacement for Google Drive
Proton Drive — strong privacy reputation and a polished ecosystem.
Best for highly sensitive documents
Tresorit — designed around secure file sharing and business compliance.
Best if you want a simple, familiar cloud drive
Sync.com — similar workflow to mainstream cloud storage but privacy-focused.
Best for teams with large active files
LucidLink — built for collaborative workflows while keeping encryption keys under customer control.
A few cautions:
If you lose your password/recovery key with a true zero-knowledge service, the provider usually cannot restore access.
“Encrypted at rest” is not enough—many normal cloud providers encrypt data but still hold the keys.
Check whether file names and metadata are also encrypted; some services protect file contents but expose some metadata.
If you tell me your priority—lowest cost, maximum privacy, open source, self-hosting, business use, or easiest replacement for Dropbox—I can narrow this down.
Filen — Completely open-source, zero-knowledge cloud storage that runs client-side encryption with a clean interface and affordable pricing/lifetime options.
Cryptomator — Not a cloud host itself, but a tool you can use to add a zero-knowledge encryption layer on top of existing providers like Google Drive, Dropbox, or OneDrive.
Note on password recovery: Because these providers have zero knowledge of your keys or password, if you lose your master password or recovery phrase, they cannot reset it or recover your data for you.
To help narrow down the best fit, tell me:
How much storage capacity do you need?
Do you prefer a subscription or a lifetime plan?
Are you looking for collaborative editing features, or strictly backup and storage?
If your priority is that the cloud storage provider must never have access to your encryption keys or be able to read your files, look for a service with zero-knowledge, client-side end-to-end encryption (E2EE).
I've found three strong candidates: Proton Drive, Tresorit, and Filen. All three describe security architectures designed to prevent the provider from decrypting your stored files.
Best zero-knowledge cloud storage providers
1. Proton Drive
(Best overall starting point)
Best for personal files, photos, and documents
Proton says your files and their names are end-to-end encrypted, and it cannot access your private encryption key. Encryption happens automatically, so you don't have to manage keys manually.
Why choose it: A straightforward, privacy-focused alternative to Google Drive or OneDrive.
Best for business, sensitive documents, and collaboration
Tresorit encrypts files on your device and says encryption keys are never sent to its servers in readable form. It also offers secure file sharing and team-oriented features.
Why choose it: Strong confidentiality combined with business and collaboration tools.
Key ownership: Confirm the provider cannot decrypt your files, including through account recovery or administrator access.
Recovery options: If you lose your password or recovery key, your files may become permanently inaccessible. Understand the recovery process before uploading important data.
Independent verification: A provider's security claims are a starting point. Review published technical documentation, independent audits, and whether the client apps are open source.
One important distinction: zero-knowledge encryption protects file contents, but it doesn't necessarily hide all account information, access patterns, or metadata.
My recommendation: Start with Proton Drive for a convenient personal solution, or Filen if open-source transparency is a particularly high priority.
To narrow this down further: Are you looking for personal storage or business storage, and approximately how much space do you need? That will help identify the best fit for your budget and security requirements.
Yes. I’d focus on providers where encryption happens on your device and the provider never possesses the decryption keys—not merely services that advertise “encrypted at rest.”
Best options
Provider
Zero-knowledge / provider can't decrypt
Key control
Best for
Proton Drive
✅
You control the private key
Best overall
Tresorit
✅
Keys remain under your control
Security-focused/business use
Internxt Drive
✅
Keys held only by you
Privacy + open source
Sync
✅
Zero-knowledge architecture
Straightforward cloud sync
My first choice: Proton Drive. Proton says files, filenames, and folder names are encrypted on your device before upload, and that Proton does not have access to your private key. Its apps and encryption implementation are also open source and independently audited.
Tresorit is another particularly strong choice. It explicitly states that encryption keys are generated/managed locally and are never shared with Tresorit in readable form.
Internxt Drive is worth considering if you prioritize open source and newer cryptography. Internxt says files are encrypted client-side and that it never has your encryption keys; it also currently advertises post-quantum encryption.
“Zero-knowledge” doesn't necessarily mean zero metadata. For example, Proton says file contents and names are encrypted, while certain information such as file size remains available to its servers. proton.meproton.me Internxt similarly says file/folder names, structure, sizes, and timestamps can remain server-side metadata.
If your requirement is “the provider must cryptographically be unable to decrypt my files, even if compelled or hacked,” I'd shortlist Proton Drive, Tresorit, and Internxt first.
If you need true zero-knowledge privacy where the provider cannot access your encryption keys or read your data , you want a service that performs client-side encryption . This means your files are scrambled on your device before they ever leave for the cloud.[](https://www.dragbin.com/blog/zero-knowledge-cloud-storage/)
Here are the top zero-knowledge cloud storage providers that do not have access to your keys:
Cryptomator : If you prefer to keep using an existing standard cloud provider (like Google Drive, OneDrive, or Dropbox) but want absolute zero-knowledge security, Cryptomator acts as a client-side encryption layer that locks your files before they sync to the cloud.
Note: Because these providers do not have your keys, if you lose your account password and any recovery phrases provided during setup, they cannot recover your data for you. [](https://www.dragbin.com/blog/zero-knowledge-cloud-storage/)
To help narrow down the best fit, let me know:
How much storage space do you need?
Do you need strong collaboration/sharing features , or is this strictly for private personal backup?
