Proton’s quiet, stubborn mission to turn privacy into a product just picked up a new, unflashy muscle: spreadsheets. This week, the Swiss company unveiled Proton Sheets, an end-to-end encrypted spreadsheet that looks and behaves much like the cloud grids millions of people live in every day—but with an insistence that no one outside your explicitly shared circle, not even Proton, can read what’s inside.

On the surface, Sheets is deliberately familiar. A blank white grid, a toolbar where you expect it, cells that accept formulas, charting tools, and the ability to import CSV and XLS files so you don’t have to rebuild the spreadsheets that actually run your life or business. That “boring” familiarity is the point: Proton wants to lower the friction of switching from Google Sheets or Microsoft Excel, so teams don’t have to retrain, retool, or rip workflows apart just to keep their numbers private. The product pages and early reviews underline the ship-shape feature set—basic formulas, charts, and imports are supported—so it can slot into day-to-day work quickly.

Where Proton tries to change the rules is under the hood. Every piece of a Sheets file—cell values, formulas, charts and even metadata like filenames—is encrypted end to end, meaning the keys to decrypt live with the users, not on Proton’s servers. In other words, the company says it cannot and will not read your spreadsheets. That matters because modern cloud office suites increasingly fold in features—AI assistants, analytics tooling, telemetry—that can require provider access to data, or at least create gray areas about how that data might be used. Proton’s pitch: you can keep the collaboration you need without turning your spreadsheets into a free training set.

Sheets isn’t a standalone vanity project; it lives inside Proton Drive, the company’s encrypted cloud storage. If you already use Drive, you’ll find Sheets under the New menu; if not, you can sign up and try it—Proton is rolling the feature out to Drive users and making it available on the free tier. That integration is an explicit play to offer a full-stack, privacy-first workspace where mail, calendars, documents and spreadsheets all live under the same legal and technical guardrails—in Proton’s case, Swiss privacy law. For teams that want to consolidate and tighten their data posture, being able to keep everything inside one encrypted ecosystem is a compelling argument.

But Proton is playing a patient game: Sheets covers the everyday spreadsheet needs first. Real-time collaboration is supported—live editing, sharing controls, the ability to grant or revoke view/edit rights—so a small agency or startup can keep working the same way while ensuring sensitive rows and formulas don’t leak into someone else’s systems. The tradeoff is obvious to anyone who’s ever lived in Excel’s deepest corners: Proton isn’t trying to out-feature Microsoft on macros or niche financial functions on day one. Instead, it’s saying the vast majority of workflows are “good enough” when privacy is the stake. Early reporting and hands-on takes emphasize that balance—familiar collaboration plus a privacy-first encryption model.

That positioning is plainly a response to the new anxieties around AI. Over the past two years, big cloud providers have aggressively embedded “copilot” features inside Docs and Sheets—features that promise productivity boosts but often come with terms that allow providers to use customer data to train models unless businesses explicitly opt out. Proton is trying to sell a different bargain: convenience without the opaque downstream use of your data. For companies worried about contractual exposure, regulatory audits, or accidentally seeding proprietary IP into someone else’s training corpus, an encrypted spreadsheet is no longer a niche privacy experiment but a practical risk-management choice.

For users who run their operation from spreadsheets—editorial calendars, finance models, campaign trackers—the real question will be how much they value “privacy by default” over the extended ecosystem that Google and Microsoft offer: connected add-ons, AppScript automations, third-party integrations, and power features that have been built up over decades. Proton’s early moves suggest it knows that: Sheets is designed to make migration easy (import CSV/XLS), to minimize workflow disruption (familiar UI, sharing controls), and to scale outward from there (Docs already launched last year). The company’s bet is that more organizations will be willing to trade the extremes of power-user depth for a guarantee that their spreadsheets aren’t quietly ingested by someone else’s algorithm.

There are practical wrinkles. End-to-end encryption in collaborative apps is technically hard and sometimes makes third-party integrations or complex server-side features difficult to implement; if your workflow depends on an ecosystem of plug-ins or advanced automation, Proton will take time to catch up. Also, because the encryption model removes provider access, certain server-side conveniences—like provider-run AI assistants that process your sheet server-side—aren’t straightforwardly possible unless Proton builds privacy-safe ways to offer similar features. For many users, that’s an acceptable compromise; for others, it will be a dealbreaker.

For Proton, Sheets is another step toward a single-vendor alternative to the mainstream suites—one that leans on legal jurisdiction as well as engineering to make a privacy promise. The company has been explicit about its target: individuals, small teams and businesses that are “privacy-first” by principle or necessity. Whether those audiences are large enough to bend entrenched enterprise habits remains to be seen, but the launch does make the competition over productivity tools more interesting. Privacy used to be a checkbox; Proton is trying to turn it into a line item on the feature comparison chart.

In practice, that could change how some people choose tools. A consultant sharing client lists, a newsroom tracking sensitive story budgets, or a tiny startup modeling runway may all find the idea of a spreadsheet that cannot be read by the vendor reassuring. Migration is easier than it used to be—imports work, the interface is familiar, and sharing behaves like other cloud tools—so Proton’s “good enough plus privacy” pitch might be exactly enough for a lot of teams to switch. Whether Proton can keep pace on features while holding the line on encryption will determine if Sheets becomes a fringe privacy play or a mainstream alternative to the big names.

If you want to try it, Proton Sheets is available in Proton Drive and rolling out to users now; expect the company to iterate quickly if uptake follows. The spreadsheet may look boring—rows, columns, formulas—but in an era where data privacy increasingly shapes product choices, a seemingly mundane grid can be a surprisingly political and practical battleground.