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 client-side/end-to-end encryption where the provider does not possess the decryption keys, these are strong options:

• Proton Drive — My top pick for most individuals. Files are encrypted on your device before upload, and Proton says it cannot decrypt them. It also encrypts filenames and folder names. There’s a 5 GB free tier.
• Tresorit — Particularly strong if security and business collaboration are priorities. Tresorit explicitly says encryption keys are generated/managed client-side and are never available to Tresorit in readable form.
• Sync.com — Another good choice. Sync says files are encrypted before leaving your device and that it does not have the keys needed to decrypt them.

My recommendation

For personal use: Proton Drive. It gives you a straightforward Google Drive/Dropbox-like experience while maintaining end-to-end encryption, and its current free plan includes 5 GB.

For maximum security/collaboration: Tresorit. Its zero-knowledge architecture is particularly explicit about keeping encryption keys away from the provider.

One important caveat: zero-knowledge means you also need to protect your account credentials/recovery mechanisms carefully. If the provider genuinely cannot decrypt your files, it generally can't simply recover the underlying encryption keys for you if you permanently lose the necessary credentials.

If you tell me how much storage you need (e.g. 100 GB, 1 TB, 5 TB) and whether you're using Windows, Mac, iPhone, or Android, I can narrow these down by price, privacy model, and ease of use.

If you want true zero-knowledge, client-side encryption where your keys never leave your device and the provider has zero technical means to read your files or reset your password, you want a service designed with end-to-end encryption (E2EE) by default.

Top cloud storage providers that meet this strict requirement include:

• Sync.com : Based in Canada, Sync offers zero-knowledge storage built straight into the core platform. They don’t have access to your password or keys, meaning if you lose your credentials, they cannot recover your data for you. It handles file syncing and sharing very smoothly.
• Tresorit : Headquartered in Switzerland (under strict Swiss privacy laws), Tresorit uses client-side zero-knowledge encryption for all data and shares. Even their authentication mechanism is zero-knowledge, meaning your password never reaches their servers in plaintext.
• Proton Drive : Coming from the privacy ecosystem behind Proton Mail, Proton Drive applies zero-knowledge encryption to your files, file names, and metadata automatically on every plan. Their apps are open-source and independently audited.
• Filen : A smaller, highly privacy-focused, zero-knowledge cloud storage provider based in Germany. It features completely client-side, open-source end-to-end encryption with zero provider access to keys.
• NordLocker : Built by the team behind NordVPN, NordLocker specializes in zero-knowledge file encryption both locally on your hardware and in the cloud. Like others on this list, your master password is your key, and they cannot restore your account if you lose it.

Note on providers like MEGA, pCloud, or IDrive: While MEGA is zero-knowledge by default, and pCloud or IDrive offer zero-knowledge tiers (often as an add-on or specific folder like pCloud Crypto), the options listed above enforce strict zero-knowledge architecture across the board without relying on opt-in server settings.

To help narrow down the best fit, tell me:

• How much total storage space do you need?
• Do you require real-time document collaboration or just secure file backup/syncing?
• What operating systems/devices will you be using most?

To achieve complete data privacy where the service provider cannot read your files, reset your password, or access your encryption keys , you need a provider that enforces client-side, zero-knowledge encryption by default.

The top cloud storage providers that meet these strict security requirements include:

🔎 Top True Zero-Knowledge Providers

• Proton Drive : A highly trusted, Swiss-based provider. It encrypts all file data, metadata, and folder names on your local device before upload. The service is fully open-source and audited.
• MEGA : Out of the box, it provides a generous 20 GB free tier with full zero-knowledge encryption. Your password acts as the master decryption key; if lost, MEGA cannot recover it.
• Tresorit : An enterprise-grade, ultra-secure option based in Switzerland. It is heavily audited by PwC and focuses on compliant, secure team collaboration. There is no free tier available.
• Sync.com : A Canadian-based provider compliant with strict privacy laws. It applies zero-knowledge protection across your entire account by default.
• Filen : A Germany-based, open-source provider that focuses on strict zero-knowledge architecture. It is a budget-friendly option with independent security audits.
• Internxt : A unique provider that features decentralized architecture. It shreds your encrypted files into pieces and distributes them across distinct global servers. It also features post-quantum cryptography.

⚠️ Providers to Use with Caution

• pCloud / Dropbox : Both market "zero-knowledge" options, but they are limited. pCloud charges an extra fee for a specific "Crypto" folder, while Dropbox only applies it to specific folders on expensive business plans. The rest of your account is not zero-knowledge.
• Google Drive / OneDrive / iCloud : These mainstream providers handle encryption keys on their own servers. This allows them to scan your files, preview documents, and hand over data to law enforcement if legally compelled.

💡 The Trade-offs of True Zero-Knowledge

Before moving your data, keep these architectural limitations in mind:

• No Password Resets : Because the provider does not have your keys, they cannot reset your password. If you lose your master password or recovery key, your data is lost forever.
• Limited Search : You can search files by their names, but you cannot search text inside documents because the server cannot read them.
• No Server-Side AI : Features like automatic photo categorization, facial recognition, or document summarization are impossible.

🌟 Pro Tip: The "Bring Your Own Encryption" Alternative

If you prefer to keep using a mainstream provider like Google Drive for its speed and features, you can use Cryptomator . It is a free, open-source tool that encrypts your files locally into a secure "vault" before syncing them to any cloud provider, turning any standard cloud into zero-knowledge storage.

To help narrow down your choice, let me know:

• What storage capacity (e.g., 20 GB, 2 TB) do you need?
• Do you require advanced team collaboration or just personal file backups?
• Are you looking for a free tier , a monthly plan, or a lifetime license?

Yes. If your requirement is true zero-knowledge / client-side encryption where the provider does not possess your decryption keys, I’d shortlist these:

My top pick: Proton Drive

proton.me explicitly states that files are encrypted on your device before upload, and that Proton does not have access to your private encryption key. File contents, filenames, and folder names are end-to-end encrypted.

It also has a free 5 GB plan, so you can test it without committing.

If security is the absolute priority: Tresorit

tresorit.com is particularly strong on the specific requirement you mentioned. Tresorit says its encryption keys are generated and managed locally and never shared with Tresorit, meaning the company cannot decrypt your files.

One important distinction

Don't assume that a service advertising "encrypted cloud storage" is zero-knowledge. With ordinary encryption, the provider may hold the keys and therefore technically be capable of decrypting your files. What you want is client-side encryption + zero-knowledge architecture, where the provider never receives the usable decryption key.

If I were choosing today: I'd use Proton Drive for personal use and Tresorit for especially sensitive/business data.

If you tell me roughly how much storage you need (e.g. 500 GB, 2 TB, 5 TB) and whether you need Windows/Mac sync, phone photo backup, or family sharing, I can narrow it down to the best-value option.

To achieve complete data privacy where the service provider cannot read your files, reset your password, or access your encryption keys , you need a provider that enforces client-side, zero-knowledge encryption by default.

The top cloud storage providers that meet these strict security requirements include:

🔎 Top True Zero-Knowledge Providers

• Proton Drive : A highly trusted, Swiss-based provider. It encrypts all file data, metadata, and folder names on your local device before upload. The service is fully open-source and audited.
• MEGA : Out of the box, it provides a generous 20 GB free tier with full zero-knowledge encryption. Your password acts as the master decryption key; if lost, MEGA cannot recover it.
• Tresorit : An enterprise-grade, ultra-secure option based in Switzerland. It is heavily audited by PwC and focuses on compliant, secure team collaboration. There is no free tier available.
• Sync.com : A Canadian-based provider compliant with strict privacy laws. It applies zero-knowledge protection across your entire account by default.
• Filen : A Germany-based, open-source provider that focuses on strict zero-knowledge architecture. It is a budget-friendly option with independent security audits.
• Internxt : A unique provider that features decentralized architecture. It shreds your encrypted files into pieces and distributes them across distinct global servers. It also features post-quantum cryptography.

⚠️ Providers to Use with Caution

• pCloud / Dropbox : Both market "zero-knowledge" options, but they are limited. pCloud charges an extra fee for a specific "Crypto" folder, while Dropbox only applies it to specific folders on expensive business plans. The rest of your account is not zero-knowledge.
• Google Drive / OneDrive / iCloud : These mainstream providers handle encryption keys on their own servers. This allows them to scan your files, preview documents, and hand over data to law enforcement if legally compelled.

💡 The Trade-offs of True Zero-Knowledge

Before moving your data, keep these architectural limitations in mind:

• No Password Resets : Because the provider does not have your keys, they cannot reset your password. If you lose your master password or recovery key, your data is lost forever.
• Limited Search : You can search files by their names, but you cannot search text inside documents because the server cannot read them.
• No Server-Side AI : Features like automatic photo categorization, facial recognition, or document summarization are impossible.

🌟 Pro Tip: The "Bring Your Own Encryption" Alternative

If you prefer to keep using a mainstream provider like Google Drive for its speed and features, you can use Cryptomator . It is a free, open-source tool that encrypts your files locally into a secure "vault" before syncing them to any cloud provider, turning any standard cloud into zero-knowledge storage.

To help narrow down your choice, let me know:

• What storage capacity (e.g., 20 GB, 2 TB) do you need?
• Do you require advanced team collaboration or just personal file backups?
• Are you looking for a free tier , a monthly plan, or a lifetime license?

Yes. If your requirement is specifically zero-knowledge / client-side encryption where the provider does not possess the decryption keys, these are strong options:

• Proton Drive — Files, filenames, and folder names are encrypted on your device before upload. Proton says it does not have access to your private key, so it cannot decrypt your files.
• Tresorit — Particularly strong if security is the priority. Encryption keys are generated/managed client-side and aren't available to Tresorit; its zero-knowledge model applies to stored files and sharing.
• Sync.com — Encrypts files before they leave your device and states that it doesn't have the keys needed to decrypt them. It also offers a free tier/trial options depending on the plan.

My pick

For most individuals: Proton Drive. It gives you a polished mainstream cloud-drive experience while maintaining end-to-end/zero-access encryption, and its ecosystem is a nice bonus if you also use Proton Mail/VPN/etc.

For maximum security and business use: Tresorit. Its zero-knowledge architecture is especially explicit about keeping encryption keys under the customer's control.

One important distinction: "encrypted at rest" is not enough. Google Drive, Dropbox, OneDrive, etc. encrypt your data, but the provider generally retains the ability to decrypt it. What you want is client-side/end-to-end encryption where the provider never receives the usable keys.

If you tell me your priorities (e.g. cheapest, 1–5 TB, best for photos, Windows/Mac sync, or strongest privacy), I can narrow this to the best 1–2 choices.

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.