Proton Launches 'Lumo,' A Privacy-First AI' Where 'Conversation Is Confidential': A Different Philosophy

In the era where large language models are becoming more than just a tool, the market is thriving, the demand is high.

Following OpenAI ChatGPT's arrival, tech companies began involved in an arms race, where they try to outpace one another, in order to create the best out of the best LLMs. Proton, a privacy-focused company, also wants a share of this massive pie.

However, it wishes to be different. It's selling point? The way it respects privacy.

Whereas most AI tools from Big Tech companies thrive (and get smarter) by collecting and monetizing user data, Lumo was built with a different philosophy: to empower users without compromising their privacy or security.

According to Proton, this Lumo can bring all the benefits of modern AI, but without the trade-offs that put personal information at risk.

Based on the fact that Proton is the creator of both Proton Mail and Proton VPN, both of which are privacy-focused tools, Lumo does come from a lineage of privacy-first services. It's developed by those who have spent years building secure digital tools, and it’s owned by a Swiss nonprofit whose mission is to defend privacy.

According to Proton, its business model is unlike profit-driven tech giants, and that Proton will never make money by exploiting user data.

From the very foundation, Lumo was engineered with total privacy in mind. Instead of logging user interactions, storing prompts, or using them to train future versions of the model, Proton adopted a strict no‑logs, no‑training, and no‑retention policy.

In order to create this bot, Proton developed Lumo using a multi-model open-source LLM strategy hosted entirely on Proton-controlled European data centers. The current models include Mistral Nemo, Mistral Small 3, Nvidia OpenHands 32B, and Allen Institute’s OLMO 2 32B.

Proton then trained the models on public, curated datasets up until around October 2023, and no user conversations are added to that training corpus. This guarantees that user data never ends up in someone else’s assistant output.

Proton automatically routes user queries to the most suitable model—for example, programming or code generation tasks go to OpenHands, which is tuned specifically for that domain.

All models and code are open source, meaning anyone can audit how the system handles data, ensuring transparency and privacy compliance

Features include Ghost Mode that allows conversations to vanish entirely whenever users close them, an optional web search that is disabled by default, secure file handling where Lumo can analyze documents in real time before discarding them.

Users can use Lumo for free through the web at lumo.proton.me or on mobile devices without requiring a Proton account. Free users get access to a limited number of chats per week and basic encrypted chat history. With a Proton account, they can sync encrypted chat history across devices using zero‑access encryption.

But for power users, the Lumo Plus subscription which comes at a price removes limits on chat volumes, allows larger file uploads, and extends history retention.

To ensure that it's true to its words, Lumo makes all conversation confidential.

For starters, it keeps no logs of chats, meaning that whatever users ask, what Lumo replies, and how users interact with the bot are never stored.

"Lumo saves nothing on our servers," the company says, meaning that there should be no profiling, no surveillance, and no backdoor access.

However, if users wish to save their conversation, they're able to do so, but they're protected by zero-access encryption. What this means, only the users themselves can access them, and not even Proton can decrypt or view them.

What's more, the data isn't shared with advertisers, governments, or anyone else.

"Lumo is a European service subject to GDPR, so you can delete your data anytime," the company says.

Lumo is also open source, so anyone can inspect it and verify that the privacy claims are real.

Long story short, Proton wants Lumo have have privacy not as a feature. Instead, it wants it to be its foundation.

Lumo stands as a bold statement in today’s AI landscape—proving that intelligence and integrity can coexist. At a time when many assistants trade privacy for personalization, Proton has chosen a different path, building a tool that serves users without surveilling them. Whether it's used for writing, researching, or simply asking questions, Lumo delivers answers without compromising their trust.

By combining open-source transparency, zero-access encryption, and Proton’s long-standing commitment to user-first security, Lumo offers a refreshing alternative to Big Tech's data-hungry systems.

In other words, Lumo wants to be more than just an AI assistant—it's a commitment to a future where privacy and innovation go hand in hand.