🟢 Trust Rating: High
Start with what is wrong. As of July 2026 there is still no native Linux desktop app, only a command-line tool that shipped in June 2026 for scripted uploads and backups. Uploads were for years among the slowest in encrypted storage, the tax you pay for encrypting every file on your own device before it leaves; Proton says a June 2026 rebuild made uploads up to three times faster, but that fix is very new and layered on a long-standing complaint. The server-side code is closed and its raw API is undocumented, so "open source" here means the apps on your device, not the whole stack. Consumer support is email only, and Drive-only pricing looks expensive next to plain storage unless you also want Proton Mail, VPN, and Pass in the same bundle. Now the case for trust: Proton Drive is end-to-end encrypted by default, and that encryption covers file contents, file names, and folder structure, not just the file body, so Proton cannot read your files or even see what you named them. The client apps are open source under GPLv3, the provider is a Swiss company whose primary shareholder is a non-profit foundation, and the company holds ISO 27001 certification and a SOC 2 Type II attestation. The honest ceiling: the only external audits aimed at Drive itself were run by Securitum in 2021 (web app) and 2022 (mobile apps), and we found nothing newer specific to Drive. It earns a high rating for the encryption model and the provider, with that audit-age caveat attached.
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Try Proton Drive →What is Proton Drive?
Proton Drive is the encrypted cloud-storage arm of Proton AG, the same Swiss company behind Proton Mail, Proton VPN, Proton Pass, and Proton Calendar. It stores files, photos, documents, and spreadsheets in end-to-end encrypted form, and it now includes collaborative document and spreadsheet editors on top of plain storage.
The product took a slow road out of beta. A paid beta opened on November 16, 2020, a free beta followed in June 2021, and the public web app exited beta on September 22, 2022. The iOS and Android apps arrived on December 7, 2022, the Windows desktop app on July 12, 2023, and the macOS desktop app on November 23, 2023. Note what is missing from that list: a native Linux desktop client, which still did not exist in mid-2026.
The governance is the same story as the rest of Proton. On the tenth anniversary of the company in June 2024, Proton AG was placed under the Proton Foundation, a Swiss-registered non-profit endowed with enough shares to be Proton AG's primary shareholder, with dual cantonal and federal foundation oversight and an annual audit. The founding board of trustees includes Andy Yen, Antonio Gambardella, Oxford ethics professor Carissa Véliz, web inventor Tim Berners-Lee, and Dingchao Lu. Proton AG remains a for-profit operating company and has pledged to allocate 1% of its net revenues to the foundation whenever financial conditions allow. Swiss foundations have no shareholders in the ordinary sense, which is the point of the structure, and this site treats it as a real trust signal.
Critical Privacy Concerns
⚠️ What You Are Actually Trusting
- Still no Linux desktop app. In June 2026 Proton shipped a cross-platform command-line tool, proton-drive, for Windows, macOS, and Linux, aimed at scripted uploads, backups, and automation. That is not a graphical sync client. The full Linux GUI app is described by Proton as in active development on its new Drive SDK, with no committed release date; secondary reports cite an internal goal of before the end of 2026, which is a goal and not a promise. In the meantime, Linux users make do with unofficial community clients and an rclone backend that is still labeled beta. A March 2026 rclone issue is openly soliciting a maintainer to re-implement Proton Drive support against Proton's new SDK, so treat the current rclone path as unmaintained relative to Proton's platform changes.
- Uploads were long the slowest around. For years reviewers ranked Proton Drive near the bottom on upload speed against competitors like MEGA and pCloud, a direct cost of encrypting every file on the client before it uploads, which hits large numbers of small files hardest. Proton's June 2026 SDK rebuild claims up to three times faster uploads, up to two times faster downloads, and up to four times faster file encryption. That is a genuine improvement, but it is a very recent patch on a complaint that ran for years, so judge it on your own connection rather than on the launch numbers.
- No block-level sync, and sync that reviewers call less smooth. Reviewers report that Proton Drive lacks block-level (delta) sync, so changing one line in a large file re-uploads and re-encrypts the whole file rather than only the changed bytes. Separately, some users report sync pausing until the app is restarted, and files that appear and disappear across devices. These come from review-site testing rather than Proton's own documentation, so weight them as reported friction, not confirmed defects, but they are consistent enough to flag.
- Closed server, undocumented raw API. The client apps are open source; the backend is not, and Proton has never published its server code or raw Drive API documentation. The original rclone backend only existed because a developer reverse-engineered the protocol from the open client source and network traffic; since 2026 Proton offers an open-source Drive SDK (MIT) as the official integration path, though Proton itself says it is not yet ready for third-party production use. You are still trusting Proton's cloud on the parts you cannot inspect.
- Ecosystem cost and lock-in. Priced as storage alone, Proton Drive looks expensive next to mainstream storage-only services. The math only works if you also want Proton Mail, VPN, and Pass, which is exactly the bundle Proton is selling. Consumer support is email only, with no live chat, and some users report friction moving or copying large numbers of files in the web app. Concentration risk cuts the same way: one Proton account now reaches your mail, your passwords, and your files at once.
- The Swiss jurisdiction is under political pressure, and the servers are moving. Switzerland floated a revision to its VÜPF surveillance ordinance that would have forced providers with as few as 5,000 users to log IP addresses for six months and be able to strip encryption they provide; CEO Andy Yen said Proton "would have no choice but to leave Switzerland." After public pushback the revision was sent back for an external review and remains unresolved as of mid-2026. Ahead of that, Proton is relocating the majority of its physical server infrastructure out of Switzerland to the EU (Germany) and Norway, a reported investment of more than €100 million, with its Lumo AI product the first to move to Germany. A Proton spokesperson told TechRadar that "investing in Europe does not equate to leaving Switzerland," and the company stays legally Swiss-domiciled. Treat the Swiss advantage as real today rather than guaranteed tomorrow.
Security Architecture and Audits
The encryption model is the strongest part of the product and it is documented in public. Proton Drive encrypts far more than the file body. File contents are split into blocks of up to 4 MB each, and each block is signed with a hash so it cannot be tampered with or reordered. The file or folder name is encrypted with the parent folder's key, so the folder tree itself is hidden, and each node also keeps metadata such as type, size, and creation and modification time. All of this happens on your device before upload, under a hierarchical tree of per-node keys and passphrases that cascade from parent to child and are signed with your address key, so the server cannot forge them. The practical result: Proton cannot read your files, and it cannot see what you named them or how you organized them.
Be honest about the edge of that protection. Proton's own Drive threat-model page focuses on file contents and metadata; it does not claim to hide network-level signals such as the number of files you hold, the approximate size of files inferred from encrypted block sizes, access timestamps, or your IP address. Those remain visible to Proton and to anyone watching its infrastructure, to some degree. This is the standard limit of most end-to-end encrypted storage, not a Proton-specific weakness, but it is the difference between "content confidential" and "activity invisible," and the second is not on offer.
On open source, the current active client code lives in the ProtonDriveApps organization on GitHub (android-drive and ios-drive, licensed GPLv3-or-later) plus the web client in Proton's web-clients repository. An older 2021-era Drive repository is archived and read-only, so ignore stale links pointing at it. The backend stays closed.
Audits are where Drive is weaker than its sibling Proton Pass, and this site will not paper over it. The Drive web app was independently audited by Securitum in October 2021, and the Android and iOS apps by Securitum in August and September 2022, with a low-severity Android finding about local storage of cookies and certificates that required physical access to the device to exploit. The source code for the mobile apps was published on March 2, 2023 alongside those audit reports. Proton's current Drive security page still says "Proton Drive has been audited by Securitum" without pointing to anything newer, and we found no Drive-specific third-party audit dated 2024, 2025, or 2026, and no published Cure53 report covering Drive specifically. Company-wide, Proton earned ISO 27001 certification on May 2, 2024 and completed its first SOC 2 Type II attestation, audited by Schellman, in July 2025. Read those in scope: they cover Proton's information-security management broadly, not a fresh line-by-line audit of Drive.
For the record on scare headlines: a 2025 report by Venak Security, framed by some outlets as putting "500 million" Proton users at risk, concerns Proton VPN and Proton Pass, not Drive, and Proton published a point-by-point rebuttal calling the described memory behavior normal rather than a vulnerability. We found no Drive-specific CVE or confirmed breach in this research.
Features That Matter
Be precise about the free tier, because the marketing rounds up. A new account starts at 2 GB of base storage and only reaches 5 GB total after you complete three onboarding actions within 30 days: add a file or folder, create a shareable link, and set up a recovery method. So the "5 GB free" figure you see elsewhere is 2 GB you get on day one plus a bonus you have to earn.
- Encrypted documents and spreadsheets: Proton Docs, an end-to-end encrypted collaborative document editor, launched July 3, 2024. Proton Sheets, an encrypted spreadsheet with real-time co-authoring, formulas, charts, and Excel and Google Sheets import, launched December 4, 2025. Both work on free and paid accounts.
- Photo backup and albums: photo backup arrived on Android in December 2023 and reached iOS around June 20, 2024. Encrypted, collaborative photo Albums launched May 14, 2025.
- Version history: file version history was introduced May 16, 2023, and later expanded so Unlimited subscribers can keep up to 200 versions of a file for up to 10 years.
- Offline access is selective, not automatic: the Windows and macOS desktop apps use on-demand sync where you right-click "Always keep on this device," and mobile apps let you mark a file "Make available offline." Pure web use needs a connection; there is no offline web mode.
- Desktop and CLI: graphical desktop apps for Windows (July 2023) and macOS (November 2023), plus the cross-platform proton-drive command-line tool (June 2026). No Linux GUI yet.
- Performance SDK: in June 2026 Proton rebuilt Drive on a single unified SDK powering Windows, macOS, iOS, Android, and web, which it credits with the up-to-three-times-faster uploads and up-to-two-times-faster downloads mentioned above.
- Business tier: Proton Drive for Business launched August 2024 with team storage, Docs, 2FA, Proton Sentinel monitoring, and version history up to 10 years, if you need file storage for an organization rather than a household.
- Money-back guarantee: paid plans carry a 30-day money-back guarantee, confirmed on Proton's Drive pricing page.
Pricing Structure
The honest framing first. Proton's pricing page renders with JavaScript and can show region-specific currency, so confirm the exact number at checkout. Proton also runs introductory promotions, for example a heavily discounted first month or first annual term, and those revert to the standard rate at renewal, so read the small print before you assume the promo price is what you keep paying. The euro figures below matched proton.me in July 2026, and the euro and US-dollar prices mirror each other; Drive Plus is €4.99 or $4.99 a month.
| Plan | Storage | Price |
|---|---|---|
| Free | 2 GB base, up to 5 GB after onboarding steps | €0 |
| Drive Plus (monthly) | 200 GB | €4.99/month |
| Drive Plus (annual) | 200 GB | €3.99/month (€47.88 billed yearly) |
| Proton Unlimited | 500 GB shared across Mail, Drive, VPN, Pass, Calendar | €12.99/month, or €9.99/month annual (€119.88/year) |
| Proton Duo | 2 TB shared, up to 2 users | €19.99/month, or €14.99/month annual (€179.88/year) |
| Proton Family | 3 TB shared, up to 6 users | €29.99/month, or €23.99/month annual (€287.88/year) |
Read the bundles carefully. Drive Plus buys you storage and nothing else. Proton Unlimited costs more per month but folds in Mail, VPN, Pass, and Calendar, so if you already pay for one of those separately, the bundle may be cheaper than the sum of the parts. If you only want a place to sync files and you do not care about the rest of Proton, a plain storage service will usually give you more gigabytes per euro.
Proton Drive vs. Alternatives
Proton Drive vs. pCloud
- Proton Drive: end-to-end encrypted by default, including file names and folder structure, open-source clients, Swiss provider.
- pCloud: offers unusual one-time lifetime pricing, but zero-knowledge encryption is a paid add-on rather than the default, and the privacy of your storage depends on picking the EU data region at signup. See our pCloud review for the region trap in detail.
Proton Drive vs. SpiderOak
- Proton Drive: encrypted by default, open-source clients, but no Linux GUI and a closed backend.
- SpiderOak: end-to-end encrypted by default with a long track record, but it is US-based and its clients are not open source. Reviewers argue the encryption design makes the US jurisdiction less relevant since SpiderOak itself cannot decrypt your data. See our SpiderOak review.
Proton Drive and the rest of Proton
Drive shares your account, your billing, and your foundation-backed provider with Proton Mail. That is convenient, and it is also concentration risk: one account compromise reaches more of your life at once. If you are weighing the email side of the same ecosystem, read our Proton Mail review.
Others worth knowing (no review page yet)
Three more services sit in the same "encrypted by default" bracket and are worth a mention even though we have not reviewed them here. Tresorit is a Zurich-based service with zero-knowledge encryption included on every plan, aimed more at business buyers and priced accordingly. Sync.com is Canadian, with zero-knowledge encryption on every tier and no add-on fees, storing data in Canadian datacenters. Cryptomator is different in kind: a free, open-source (GPL-3.0) tool that encrypts a folder on your own machine, which you then keep inside Proton Drive, Dropbox, or any other storage, so you get client-side encryption on top of a provider you already use. If your objection to Proton is the closed backend, Cryptomator plus any host sidesteps that entirely.
When to Use Proton Drive
Reasonable Use Cases
✅ You want zero-knowledge storage without a setup project. Encryption is on by default and covers names and structure, not just contents.
✅ You already live in Proton for mail, VPN, or Pass and want one account and one bill.
✅ You value encrypted Docs and Sheets for collaboration without handing the documents to Google.
Not Recommended For
❌ Linux desktop users who want a real sync client. A CLI is not a GUI, and the GUI has no committed date.
❌ Anyone moving large, frequently-edited files who needs block-level sync and top-tier upload speed.
❌ Buyers who want the cheapest gigabytes. Storage-only competitors give you more space per euro if you do not want the rest of Proton.
❌ Anyone who needs a fresh, independent audit of the storage product itself. The newest Drive-specific audit is from 2022.
The Bottom Line
Consider Proton Drive if:- You want end-to-end encryption on by default, covering file names and folder structure, with open-source clients
- You already pay for Proton Mail, VPN, or Pass and the bundle math works in your favor
- Swiss jurisdiction and a non-profit-backed provider fit your threat model
- You need a native Linux sync client or block-level delta sync today
- You want the most storage per euro and do not care about the wider ecosystem
- Recent, repeated third-party audits of the storage product are a requirement
⚠️ Final Assessment
Proton Drive gets the hard part right: it encrypts your files, their names, and their structure by default, the clients are open source under GPLv3, and the provider is a Swiss company whose primary shareholder is a non-profit foundation. That is a stronger default than most of the market, and it is why the rating is high. The honest limits are all real and worth weighing: no Linux desktop app, a closed backend, sync and speed that only recently started catching up, email-only support, and the fact that the newest audit aimed at Drive itself is from 2022 rather than this year. If your objection is the closed server, Cryptomator over any host routes around it. If you want the encryption-by-default default without building your own stack, Proton Drive is a genuinely strong pick with its rough edges named out loud.