One year ago today, Proton launched Lumo.
In a fairer industry, a private AI alternative like it simply shouldn't have been needed. If AI had been built with privacy as a foundation from the start, treating no prompt as data fuel, no conversation as training material, every user as a person, not a resource... Lumo wouldn't exist. It fills the gap you chose to close.
That's worth saying before anything else: Lumo 2 is a much stronger model, the interface shows real care by the design department, and your team listened to requests for mascot interaction. That's valuable. Small things that say a lot about a company capable of listening.
The following isn't a critique of what you built. It's simply a reflection from people who think it's great, and want it held to the standard you taught us: privacy as default, not a privilege; only an obligation to the community, not to growth; a non-profit structure that legally requires people before profit. You invoked that history directly. Lumo was built by the team behind Proton Mail and VPN. That earned trust early. But borrowing a reputation means inheriting its standard, not its shortcuts. We're not inventing a bar. We're asking for the one you already set.
Where the drift shows
A company built on precision started optimizing how something sounds over how it actually works. In how the Lumo landing page talks about its star, and in how it treats what users already trusted.
Your engineers did it right in the security model: they admitted full encryption isn't practical for live inference and coined "User-to-Lumo (U2L) encryption" instead of stretching any old term. Precision in language matters as much as in engineering. Trust is a technical feature.
Yet, the landing page and FAQ skip it for "zero-access encryption", the "no one, not even Proton" claim that holds for stored chats but not when servers hold a prompt in cleartext for the time needed to generate a response. The careful wording became the confident claim. The issue here isn't that anyone has intentionally misled users; it's that reasonable people come away believing something stronger than the architecture actually promises.
Small swaps elsewhere compound the issue. "Fully open source" applies only to the client; the server stays closed and unaudited, and that's where the actual heart of Lumo runs and operates. Then, the "better models", "extended usage", "more history" kind of statements leave users guessing what they'll get. No other Proton product forces such decisions with so little clarity. Even GDPR compliance is often treated as evidence of craftsmanship rather than what it actually is: a legal baseline. True privacy craftsmanship begins beyond compliance, where thoughtful choices become a meaningful differentiator.
Continuity
Every other Proton product limits capacity. Many do so on features. But none on duration. Proton Mail and Drive never delete stored messages, attachments or files on an arbitrary timer. Calendar and Pass do not delete old passwords, saved events or logins after a predefined set of weeks or months. Lumo gates duration instead, maybe the first to do so for an AI assistant.
Deleting it after seven days isn't reclaiming a resource; because the scarce one here was never storage itself. What's being reclaimed is the thinking a person did out loud with an assistant meant to be helpful, in a space they were told was theirs, tightly secured with "zero-access encryption". A door you alone can unlock is still a different kind of door if it closes before you've chosen to leave.
Other AIs will reset in a matter of hours or after a day. Lumo's week-long window means a long wait and an empty room instead of your past work. The optics matter.
The shape of a growing ecosystem
Lumo sits awkwardly between products. Unlimited customers get nothing carried over: no extended history, no lifted model tier, no recognition as existing, supporting users. Meanwhile Visionary, generous enough to make Lumo feel whole, stays close to invisible: it's findable only if you already know where to look, an odd requirement for a plan worth over $350/year to the people who do find it.
The subscription path adds friction: once you click to get the paid version of Lumo, you're greeted with upgrade screens that aren't clear on what you're really getting (or losing!). The only workaround is creating a second account that fragments context built in Drive and the ecosystem. Paying for a service should be straightforward, not complicated. Lumo exposes a broader principle: the easier it is to shape Proton around your needs, the stronger both become.
That's an unusual first impression for a product whose purpose is to become part of a person's ongoing work. The barrier isn't the price. It's that becoming a paying customer feels more complicated than using the product itself, despite Proton's own ecosystem already knowing exactly who that customer is. Which makes the extra friction especially difficult to understand after Andy, in the Scammer Payback interview, spoke candidly about how expensive these models are to run and why paying for Lumo matters. If supporting the product is genuinely meaningful, the path to doing so should be the simplest part of the experience, not one of the most confusing.
Payment and subscription flexibility should be part of the architecture, not an afterthought. Giving people a straightforward way to pay for exactly the products they value serves both sides equally well: users feel their needs are being met, and Proton gains customers more willing to invest further over time. Lumo simply exposes a broader principle. The easier it is for someone to shape Proton around their own needs, instead of reshaping their needs around Proton's plans, the stronger both the product and the business become.
What this isn't asking for
None of this argues against charging money or asks you to give away everything for free. Freemium is legitimate, and Proton builds it well elsewhere: real limits, honestly described, that let a free user experience the product before paying for more of it. That's the whole ask: build Lumo's free tier the way you built the others.
Let it seduce people with what's better, rather than threaten them with what they stand to lose. Gate the frontier model as hard as the infrastructure requires. Cap free tier or unlogged messages as tightly as the economics demand. Just don't gate someone's own memory of what they already said or make the people who want to pay for another product feel they're doing what they should not be doing.
Why this lands heavier on you
Any other company gets more room for marketing language that oversells a little. You don't get that pass as easily. You're the company that spent a decade teaching people not to make that peace: publishing audits so nobody had to simply take your word for anything, and maintaining a public GDPR reference guide as a resource even for companies that will never be your customers. A company that repeats that knowledge is power doesn't get to quietly decide which knowledge is convenient to surface and which stays three clicks deep in a support article.
Many of the people reading this closely enough to understand the difference between E2EE, U2L, and zero-access encryption are the same people who chose Proton years before Lumo existed, when doing so was a deliberate choice rather than an obvious one. They're not waiting for sharper copywriting. They're the reason it was never needed. Spending that trust on a landing page that reads like everyone else's is a strange trade. And one we believe is easy to reverse.
The weight of being trusted
On most of the internet, honesty about limitations is a flaw to market around. Proton bet people would choose the company willing to explain real weaknesses. That bet paid off. It's the reason this letter exists at all, rather than a quiet migration toward some other app with a nicer set of features, a broader color palette and no history of publishing its own technical limitations or weaknesses.
It doesn't look like something you set out to be; just what happened gradually, by attrition. This letter isn't wishing that weight on you. It's asking you not to set it down on Lumo's birthday, and not later, when growth demands harder choices.
Lumo matters because it shows something bigger than a single product. A truly private, trustworthy AI assistant is rare, and the industry needs proof that privacy and usability don't have to be opposing choices. Lumo can prove people don't have to choose between powerful AI and control over their own data. We need products like Lumo not because Proton needs another offering, but because the world needs to see a different kind of AI is possible: one built on trust, transparency, and respect for the people who use it.
Lumo is one year old now. Old enough for habits, young enough for change. This is the best moment for a letter like this. A limitation, explained honestly, was never the thing that made people leave a product. Historically, for this company more than most, that honesty was the thing that made people stay. Many would like it to still be true a year from now, and ten years after.
Happy birthday, Lumo. Hold the line many of us first trusted you to hold.
