I need a cloud storage provider that offers zero-knowledge encryption and does not have access to my keys.

Yes. If your requirement is specifically “the provider must not possess the keys needed to decrypt my files”, there are several good options.

My top picks

1. Proton Proton Drive — best overall

• End-to-end/zero-access encryption by default.
• Files, filenames, and folder names are encrypted on your device before upload.
• Proton says it does not have access to your private encryption key, so it cannot decrypt your files.
• Open-source apps and encryption libraries, with independent security audits.
• Has a 5 GB free tier.

2. Tresorit Tresorit — excellent for business/security

• Explicitly uses zero-knowledge end-to-end encryption.
• Encryption keys remain under your control and are never shared with Tresorit.
• Files are encrypted on your device before being uploaded.
• Particularly strong if you need secure collaboration and business/compliance features.

What I'd choose

For personal storage, I'd start with Proton Drive. It has the right security architecture, is relatively easy to use, and doesn't require you to manually manage encryption keys. Proton states that the private key is generated/controlled on your side and isn't available to Proton.

For business or highly sensitive professional files, I'd seriously consider Tresorit as well.

One important distinction: “encrypted at rest” is not enough. Google Drive, Dropbox, OneDrive, etc. encrypt stored data, but traditionally retain the ability to decrypt it. What you want is client-side end-to-end/zero-knowledge encryption, where the provider only receives ciphertext and doesn't possess the decryption keys.

If you tell me how much storage you need (e.g. 500 GB, 2 TB, 10 TB) and whether you're on Windows/Mac/iPhone/Android, I can narrow this down to the best 2–3 options for you.

Here are top-tier cloud storage providers that feature true client-side zero-knowledge encryption, meaning files are encrypted and decrypted on your device, and the provider never sees or stores your master password or encryption keys.

• Sync.com — Based in Canada, it offers strict zero-knowledge end-to-end encryption with seamless file sharing and collaboration tools that don't compromise privacy. You can check their plans on Sync.com.
• Tresorit — A Swiss-based provider focused on high-security and business-grade compliance, featuring zero-knowledge architecture where your keys never touch their servers. More information is available on Tresorit.
• Proton Drive — Built by the team behind Proton Mail, it utilizes open-source, end-to-end zero-knowledge encryption based in Switzerland. You can explore their ecosystem on Proton Drive.
• Mega (MEGA.io) — Provides client-side zero-knowledge encryption for all files, giving you full control over your cryptographic keys. Check out details at MEGA.
• IceDrive — Uses robust Twofish encryption alongside a zero-knowledge protocol, offering a virtual drive experience with client-side privacy. Details can be found at Icedrive.

To help narrow down the best choice, let me know:

• How much storage space do you need?
• What operating systems/devices will you be syncing from?
• Do you need file-sharing/collaboration features, or is this strictly for private backup?

Yes. What you’re looking for is true zero-knowledge / end-to-end encrypted cloud storage, where encryption happens on your device and the provider never possesses the decryption keys.

My top choices

• Proton Drive — best overall. Proton says files, filenames, and folder names are encrypted before leaving your device, and that Proton does not have access to your private key. It offers 5 GB free, with paid plans going up to 3 TB.
• Tresorit — best for serious business/security use. Tresorit uses zero-knowledge end-to-end encryption, with files and relevant metadata encrypted on your devices; its encryption keys aren't sent to its servers in unencrypted form.
• Sync.com — good value. It is widely regarded as a zero-knowledge provider with client-side encryption across its storage offering.

What I'd choose

For personal files, photos, documents, and backups, I'd start with Proton Drive. Its zero-knowledge encryption is enabled by default rather than being a special encrypted folder, and Proton explicitly states that it doesn't have your private key.

One important distinction: pCloud's encrypted storage is different—its zero-knowledge protection is an optional Crypto feature rather than the default for your entire drive.

If you tell me how much storage you need (e.g. 500 GB, 2 TB, 10 TB) and whether you need Windows/Mac, iPhone/Android, file sharing, or automatic photo backup, I can narrow this to the best 1–2 options.

If you need true zero-knowledge, client-side encryption where your files are encrypted and decrypted strictly on your device—meaning the provider mathematically cannot access your data or hold your keys—several reputable options stand out.

Here are the top zero-knowledge cloud storage providers, each with distinct strengths:

• Proton Drive: Based in Switzerland, Proton Drive uses end-to-end encryption for all files and metadata. Because keys are generated locally on your device, Proton has zero-knowledge of your data. It also integrates cleanly with their wider privacy ecosystem (Mail, Calendar, VPN).
• Sync.com: Based in Canada, Sync.com specializes in privacy-compliant cloud storage and file sharing. It features strict zero-knowledge architecture by default across all plans, excellent file-recovery tools, and seamless folder syncing without the provider ever seeing your encryption keys.
• Tresorit: A Swiss-European provider built heavily with business and heavy collaboration in mind, Tresorit offers end-to-end, zero-knowledge encryption with high-end security controls. It is more expensive than consumer-focused alternatives, but it provides polished sharing permissions and strong compliance features.
• MEGA: Offering a generous free tier (often starting around 20 GB), MEGA implements client-side encryption where you hold the master decryption key. If you lose your password/key, MEGA cannot reset it for you because they don't have it.
• pCloud: Headquartered in Switzerland, pCloud offers standard cloud storage with an optional paid add-on called pCloud Encryption . This add-on turns a designated folder into a zero-knowledge, client-side encrypted vault, giving you a hybrid of standard and ultra-secure storage.
• Internxt: An open-source, privacy-first cloud storage provider that splits your files into fragmented pieces and encrypts them client-side using zero-knowledge architecture before they hit decentralized servers.

If you tell me your storage capacity needs , your budget , or whether you need collaborative editing tools , I can help you pick the ideal provider from this list.

Yes. If your requirement is specifically zero-knowledge / client-side encryption where the provider cannot access the decryption keys, there are several good options.

My top picks

• proton.me — Best overall

• Files are encrypted on your device before upload.

• Proton says it does not have access to your private encryption key and cannot decrypt your files.

• File names and folder names are also end-to-end encrypted.

• Open-source clients and independent security audits are a plus.

• Has a 5 GB free plan.

• Particularly attractive if you also want encrypted email, calendar, and VPN from the same provider.

• tresorit.com — Best for serious business/security use

• Encryption happens locally on your device.

• Encryption keys remain under your control and are never shared with Tresorit.

• Uses zero-knowledge encryption throughout storage and sharing, including relevant metadata.

• Excellent choice if secure collaboration and business compliance are important.

What I'd choose

For personal cloud storage, I'd start with Proton Drive. It has the right security model, a free tier, and a polished general-purpose cloud-storage experience.

If your priority is maximum security for business/confidential documents, I'd seriously consider Tresorit.

One important caveat: zero-knowledge doesn't mean nobody can ever access your data. Anyone who gains access to an authorized device/account, or someone you deliberately share a file with, may be able to decrypt it. Also, losing the credentials/recovery mechanism can potentially mean losing access to the data.

If you tell me how much storage you need (e.g. 100 GB, 1 TB, 5 TB) and whether you need Windows/Mac sync, phone backup, or file sharing, I can narrow it down to the best 2–3 choices and compare their current pricing.

If you want true zero-knowledge cloud storage where encryption happens client-side and the provider never possesses or has access to your keys , several solid options fit your criteria.

Top zero-knowledge cloud providers that do not have access to your keys include:

• Proton Drive : Based in Switzerland, it features zero-knowledge, end-to-end encryption by design. Keys are generated on your device, and the open-source client-side code ensures Proton cannot read your files or hand over readable data.
• Sync.com : Headquartered in Canada, Sync provides zero-knowledge encryption by default on all plans. Your data is encrypted locally before transit, and they maintain exclusive user key custody.
• Tresorit : A Swiss-based enterprise-grade cloud provider offering zero-knowledge client-side encryption. It is heavily compliance-focused (GDPR, HIPAA) with robust audit capabilities.
• Filen : An open-source, Germany-based zero-knowledge cloud storage provider that encrypts everything client-side with zero server-side key visibility.
• MEGA : Provides client-side zero-knowledge encryption where your master key is derived straight from your password, which MEGA's servers never see in plaintext.

Note: Because these providers operate on a strict zero-knowledge architecture, if you lose your password, they cannot recover or reset your account data . You are entirely responsible for your credentials.

Would you like to compare these based on pricing tiers, storage quotas , or specific operating system integrations?

Yes. What you want is usually called zero-knowledge or zero-access, end-to-end encrypted (E2EE) cloud storage: encryption happens on your device, and the provider does not possess the private key needed to decrypt your files.

My top recommendation: Proton Drive

Proton’s Proton Drive is a particularly good fit for your requirements.

• Provider cannot decrypt your files: Proton says files and their filenames/folder names are encrypted with your private key before leaving your device, and Proton does not have access to that key.
• End-to-end encryption by default: It's not an optional encrypted folder—you get E2EE across Drive.
• Open source and independently audited: Proton publishes the code for its encrypted cloud-storage apps.
• Free tier: 5 GB, with the same encryption model as paid plans.
• Paid storage: currently extends up to 3 TB for individual plans.
• Proton's privacy policy explicitly says it cannot decrypt end-to-end encrypted Drive data, including backups.

Other providers worth considering

One important distinction: "encrypted at rest" is not enough. Google Drive, Dropbox, OneDrive, etc. encrypt your files on their servers, but the provider generally retains the ability to decrypt them. You specifically want client-side E2EE where the provider never receives your private decryption key.

If you tell me how much storage you need (e.g. 500 GB, 2 TB, 10 TB) and whether you need file sharing, photo backup, or NAS support, I can narrow this down to the best 2–3 choices and compare their current pricing.

The best cloud storage providers that feature true zero-knowledge, end-to-end encryption by default —meaning encryption keys are generated locally on your device and the provider never has access to them—include Sync.com, Tresorit, Proton Drive, Filen , and MEGA Cloud.

Top Zero-Knowledge Cloud Storage Providers

Important Trade-Offs to Keep in Mind

• No Password Recovery: Because the provider does not store your private keys or password on their servers, they cannot reset your password if you lose it. Losing your master passphrase means permanent data loss.
• Limited Server-Side Search: Server-side full-text indexing and content scanning are impossible because the servers cannot read your files. Search is typically limited to local file names on your synced devices.
• Alternative Option: If you prefer using mainstream infrastructure like Google Drive or Dropbox without trusting them with your keys, you can encrypt files locally before uploading them using open-source tools like Cryptomator.

If you share your preferred storage capacity requirements and operating systems (Windows, Mac, Linux, Mobile) , I can recommend the most practical provider or plan for your setup.

Yes. What you’re looking for is zero-knowledge / zero-access, end-to-end encrypted cloud storage, where encryption happens on your device and the provider does not possess the decryption key.

My top recommendation: Proton Drive

Proton’s Proton Drive is a particularly good fit:

• End-to-end encryption by default — files are encrypted on your device before upload.
• Proton does not have your private encryption key, so it cannot decrypt your files.
• Filenames and folder names are encrypted, not just file contents.
• Its encryption implementation is open source and independently audited.
• There is a free 5 GB plan, with larger paid plans available.
• Proton says its servers are located in Switzerland, Germany, and Norway.

One important caveat

"Zero knowledge" doesn't mean the provider knows nothing. Proton says it can still access some operational metadata, such as file permissions and creation/modification times. It cannot, however, decrypt the encrypted file contents or filenames.

If your priority is specifically "the company must never have the keys", I'd put Proton Drive near the top of your shortlist.

If you tell me how much storage you need (e.g. 200 GB, 1 TB, 5 TB) and whether you need Windows/Mac sync, phone photo backup, or NAS support, I can compare the best zero-knowledge providers for your use case.

If you want cloud storage where encryption and decryption happen client-side (meaning your device handles the keys and the provider never sees your plaintext data or your keys), several reputable, privacy-focused providers fit this exact model.

Top zero-knowledge cloud storage providers include:

• Proton Drive — Open-source, independently audited, and based in Switzerland, featuring end-to-end zero-knowledge encryption by default for all files.
• Tresorit — Swiss-headquartered enterprise-grade cloud storage with zero-knowledge encryption by default and robust compliance certifications (GDPR, HIPAA).
• Sync.com — Based in Canada, offering zero-knowledge file storage and sharing by default across all plans with strong privacy compliance.
• MEGA — Provides user-controlled end-to-end zero-knowledge encryption on all files by default, coupled with a generous free storage tier.
• Filen — Completely open-source and zero-knowledge by default, utilizing client-side encryption stored on EU-based servers.
• Internxt — Open-source, zero-knowledge provider that fragments and encrypts data client-side.
• Cryptomator — If you already use a mainstream provider (like Google Drive or OneDrive) and don't trust them with your keys, Cryptomator acts as an open-source client-side encryption layer that lets you create zero-knowledge "vaults" directly on top of your existing cloud storage.

Note on Trade-off: Because these providers have zero knowledge of your keys or password, they cannot recover or reset your account if you forget your master password. You are fully responsible for your credentials.

If you'd like to narrow this down, let me know:

• How much storage capacity you need
• Your preferred operating system or device platforms (iOS, Android, Linux, Windows, Mac)
• Whether you need collaborative editing features

I can help you pick the best-fit provider for your workflow.