Proton Drive

What Is Proton Drive?

If you don’t trust Google Drive, iCloud, or OneDrive with sensitive files, you’re basically stuck with a bad choice: convenience or privacy. Proton Drive is built for the third option—cloud storage where the provider can’t casually read your stuff, even if it wanted to.

The core pitch is simple: store and share files (and photos) with end-to-end encryption (E2EE) turned on by default, so the decryption keys stay on your devices. Proton also leans hard into “metadata protection” compared to typical cloud storage: Proton Drive says filenames, folder names, and even thumbnail previews are end-to-end encrypted.

It’s a fit for people who already live in the Proton ecosystem (Mail/VPN/Pass), and for anyone who needs “I want cloud storage, but I don’t want the provider indexing my files” more than they need best-in-class collaboration and search. Proton Drive is headquartered in Switzerland (jurisdiction: Switzerland) and uses a freemium model (free tier plus paid upgrades).

Proton Drive Features and Performance

Proton Drive’s main differentiator is that encryption isn’t an add-on. Proton states your files are end-to-end encrypted and that Proton does not have the ability to decrypt that E2EE-protected data. That matters because many mainstream storage tools encrypt “in transit” and “at rest,” but still retain server-side access.

End-to-end encryption design (and what’s actually protected)

Proton’s Drive-specific privacy policy makes several concrete claims about what’s encrypted and what isn’t. It says:

• File contents are protected with end-to-end encryption, and Proton can’t decrypt them.
• Filenames, folder names, and thumbnail previews are also end-to-end encrypted.
• Proton stores the size of the encrypted files rather than the original unencrypted file size (so the original size is obfuscated).
• Content is “cryptographically signed,” and Proton highlights signature checks as protection against forgery (for example, tampered server responses).

Proton also spells out some metadata it can access to operate the service, including file/folder creation and modification times, permissions, and the username that uploaded/created a file (their stated reason is to support signature checks / authenticity verification). This is normal in E2EE storage: “content confidential” doesn’t automatically mean “activity invisible.”

Security architecture details that impact performance

Client-side encryption can be slow if it’s implemented poorly. Proton claims Proton Drive uses client-side encryption designed for large files by splitting large files into 4 MB chunks, specifically calling this out as enabling “high-performance” E2EE. Proton also published a cryptography update stating uploads could be “up to 4x faster.” (That’s Proton’s claim; your mileage depends on hardware, file sizes, and network conditions.)

Apps, platforms, and the “open source” reality

Proton has made a major open-source move compared to most cloud storage vendors: the ProtonDriveApps GitHub organization hosts public repositories for Proton Drive clients and SDK components, including Android, iOS, Windows, and macOS apps. This is a real advantage for trust—you can inspect client code and see how encryption and key handling are implemented on-device.

Two important caveats:

1. “Open source clients” does not mean the entire service is open source. Proton’s public repos cover client-side apps/SDK pieces; the server-side backend is not presented as open source on those pages.
2. Open source also doesn’t automatically equal “audited recently.” (More on audits below.)

Sharing, versioning, and productivity features

On the feature side, Proton’s official pricing page lists:

• A free plan with 5 GB of storage.
• A paid “Drive Plus” plan with 200 GB and “10 years to recover previous file versions.”
• Proton’s web experience also includes an online document and spreadsheet editor (Proton Docs and Proton Sheets shown directly in the plan features).

Independent reviews broadly align with the idea that Drive is strong on privacy fundamentals, but still catching up on classic usability features. For example, Digital Trends’ hands-on review calls out strong encryption and cross-platform support, while also noting practical UX gaps like photo gallery search limitations and (at the time) Windows app feature gaps around photos.

Pricing and Plans

Proton Drive is freemium: there is a free plan and multiple paid tiers. On Proton’s official Drive pricing page (monthly view), the structure is:

• Proton Free: 5 GB.
• Drive Plus: 200 GB for $4.99/month (monthly billing shown).
• Proton Unlimited: bundle plan including Proton Drive storage (500 GB shown) plus Proton VPN, Proton Mail, Proton Calendar, and Proton Pass for $12.99/month (monthly billing shown).

Proton also displays a 30-day money-back guarantee directly on the Drive Plus and Proton Unlimited plan cards.

What we can say safely (based on official sources):

• There is a free tier.
• There is at least one Drive-only paid tier (Drive Plus) and at least one bundle tier (Proton Unlimited).
• Proton advertises a 30-day money-back guarantee for those paid tiers.

Exact annual prices, promo discounts, and regional currency differences change frequently; stick to what Proton shows at purchase time if you need a precise number beyond the monthly prices above.

Privacy and Security Assessment

Jurisdiction: Switzerland (good, not magic)

Proton is based in Switzerland, and Proton’s legal privacy policy states the services are operated by Proton AG in Geneva and governed by Swiss law. Switzerland is generally viewed as a stronger jurisdiction for consumer privacy than the US, but it does not make you immune to lawful requests. The practical protection here comes from E2EE: if Proton can’t decrypt your file contents, it can’t hand over plaintext contents it never has.

What Proton says it can and can’t see

Drive’s product privacy policy is unusually explicit:

• Proton states it cannot decrypt your E2EE files.
• Proton says filenames/folder names/thumbnails are E2EE.
• Proton also states it does have access to specific operational metadata (creation/modification times, permissions, uploader username).

Separately, Proton’s general privacy policy (covering the broader Proton account/services) says IP logs may be kept temporarily to combat abuse and fraud, and IP addresses may be retained permanently for Terms-of-Service breaches (and that authentication logging is optional/off by default). This is relevant to Proton Drive because Drive uses a Proton account.

Open source posture

Proton Drive’s client-side code being publicly available is a real, material trust win. ProtonDriveApps hosts public repos (Android/iOS/macOS/Windows and SDK components). Proton also publicly positions itself as an open-source privacy company and links to audit materials for Proton services.

Audits: some exist, but “recent and comprehensive” is not the story

Proton publicly states its mobile apps were independently audited by Securitum alongside making them open source, and says Securitum found no outstanding vulnerabilities in the Android/iOS apps at that time.

However, based on the third-party review landscape, a consistent criticism is audit coverage recency and scope for Drive specifically—especially for desktop apps and newer code paths. One review (State of Surveillance) argues that Drive’s audits are older and that there’s no clearly published Drive-specific audit dated 2024–2026. Treat that as informed commentary, not an official statement—but the underlying point (“audit freshness and scope are not as strong as you might hope”) is worth taking seriously if audits are your deciding factor.

Known incidents

In the sources reviewed here, we did not find a confirmed, Drive-specific breach or published CVE tied directly to Proton Drive. A third-party review explicitly states it found no Drive-specific CVE or confirmed breach in its research. If Proton Drive threat modeling is life-or-death for you, you should still assume typical cloud risks exist (account takeover, endpoint compromise, and metadata exposure), and evaluate your own operational security.

Strengths and Limitations

Strengths

• E2EE by default for stored files, with Proton stating it can’t decrypt your file contents.
• Encrypted filenames/folders/thumbnails, which is a real step up versus “content-only” encryption approaches.
• Open-source clients (public code for major apps/SDK components), improving verifiability compared to closed-source competitors.
• Long version history on paid tier (10 years listed for Drive Plus).
• Free tier exists (5 GB) for testing and light use.

Limitations / trade-offs

• Usability gaps still show up in reviews, especially around search and “Drive-like” polish compared with mainstream providers (and reviewers have called out missing/limited search and photo UX issues).
• Audit story is weaker than “best in class” if you care specifically about recent, Drive-specific third-party audits across all clients.
• Some metadata is accessible to Proton for service operation (timestamps, permissions, uploader username). That’s not unusual for E2EE storage, but it matters if your threat model includes metadata correlation.
• Encryption adds overhead: Proton itself has had to ship cryptography/performance updates to improve upload speed, which implies performance is a moving target.

Who Should Use Proton Drive?

Good fit

• Privacy-first personal storage: You want cloud backup and sharing, but you don’t want the provider reading or indexing your file contents.
• People already paying for Proton: If you’re considering Proton Unlimited anyway, Drive becomes part of a single bundle (Drive + VPN + Mail + Pass + Calendar).
• Sensitive document storage: Legal/medical/journalism workflows where content confidentiality is the priority and you can tolerate rough edges.

Not a great fit

• Teams that need Google-grade collaboration and discovery: If fast search, deep third-party integrations, and “it just works everywhere” are your top priorities, Proton Drive may feel behind in day-to-day ergonomics (as reflected in hands-on reviews).
• Audit-driven buyers who require very recent, Drive-specific third-party audits across every client platform before adoption.
• People who want “zero metadata visibility” from the provider. Proton explicitly notes it has access to some operational metadata even while content and filenames are E2EE.