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Proton, the company behind the encrypted email service Proton Mail, has launched an AI assistant aimed at preserving user privacy. The new chatbot, called Lumo, can summarize documents, generate code, write emails, and more, while storing data locally on users’ devices.

Proton says it will protect this information using “zero-access” encryption, which grants users an encryption key that only they can use to view their content, preventing third parties, including Proton, from accessing the information. This helps ensure that Proton can’t share user data with advertisers or governments, or use it for training large language models, Proton says.

Image: Proton

Though Lumo comes with the ability to search the web, Proton turns this feature off by default to “give users maximum privacy.” If users enable the feature, Lumo will search the web for answers using “privacy-friendly” search engines. Additionally, Proton says Lumo can analyze uploaded files, but it doesn’t save any of its information. Users can link Proton Drive files to Lumo as well, which are supposed to stay end-to-end encrypted when interacting with the chatbot.

Proton positions its AI chatbot as an alternative to the ones offered by larger companies, like OpenAI’s ChatGPT, Meta AI, Google’s Gemini, and Microsoft Copilot. “Big Tech is using AI to supercharge the collection of sensitive user data to accelerate the world’s transition to surveillance capitalism,” Andy Yen, the CEO and founder of Proton, says in the announcement. “Our vision for Lumo is AI that puts people ahead of profits.”

Image: Proton

Lumo is powered by several open-source large language models that run on Proton’s servers in Europe, including Mistral’s Nemo, Mistral Small 3, Nvidia’s OpenHands 32B, and the Allen Institute for AI’s OLMO 2 32B model. The AI chatbot will field requests through different models depending on which is better-suited for the query. “For instance, programming-related questions are handled by OpenHands, which specializes in coding tasks,” Proton spokesperson Betsy Jones tells The Verge.

You can access Lumo now by heading to lumo.proton.me, or downloading the Lumo app for iOS and Android. Users who don’t have an account with Lumo or Proton can only ask the chatbot a “limited number” of questions each week, and they won’t be able to access their chat histories. Meanwhile, users with a free account can view an encrypted chat history, upload small files, and favorite a limited number of chats. There’s also a $12.99-per-month Lumo Plus plan for access to unlimited chats, extended encrypted chat history, unlimited favorites, and the ability to upload large files.

There’s a glut of generative AI assistants across the internet. Almost all are powered by large language models that are trained on your conversations. Now, Swiss privacy company Proton is promising a more private alternative.

The company, better known for its secure email and VPN service, is now expanding into AI with Lumo, a new assistant launching today. Like OpenAI’s ChatGPT, Google’s Gemini and Anthropic’s Claude, it’s designed to help with everyday tasks, including rewriting emails, summarising documents and reviewing code, but with a difference. Proton says it doesn’t log, store or train its models on your prompts or chats.

The big question, which we’ll find out over the coming days and weeks, is how Lumo will compare to models trained on far larger datasets. The most advanced assistants are powered by huge amounts of user data, which helps them learn patterns and understand nuance to continuously improve over time. Proton’s going for a more stripped-back, privacy-first approach.

What is Lumo?

Lumo is Proton’s privacy-first answer to the myriad generative AI assistants released over the past couple of years. Like most AI assistants, Lumo can answer questions, summarise text, rewrite emails and review code. It also supports file uploads and integrates with Proton Drive, so users can work directly with their own documents. By default, Lumo doesn’t pull in information from the internet to answer questions, but if you choose to enable web search, it will use privacy-first search engines. Proton says those queries still aren’t logged or used for model training.

Unlike ChatGPT and Gemini, Proton says conversations with Lumo are completely confidential. Chats are end-to-end encrypted, not stored on Proton’s servers and never used to train AI models, meaning the company can’t access them, share them or learn from them.

To put that into context, ChatGPT stores conversations for 30 days for safety reasons, even if you turn off chat history in the settings, which disables training but not short-term retention. Gemini can also keep prompts for up to 72 hours, even with activity tracking switched off. Claude doesn’t train on chats by default, but still holds onto them for up to a month, or longer if they’re flagged.

All three services are also based in the US, which means they can be legally required to hand over user data. Proton, by contrast, is headquartered in Switzerland, which has stricter privacy laws.

Proton hasn’t confirmed which models it’s using, but Lumo is likely built on smaller, community-developed systems rather than the massive, privately trained models behind services like ChatGPT. That could mean its responses are less detailed or nuanced, though we’ll have a better idea once the source code is released.

How to use Lumo

Lumo is available now on the web, as well as via the Lumo app for iOS and Android. There are three tiers of Lumo – two free and one paid. While you don’t need an account, guest users can only ask a limited number of questions each week, and those chats aren’t saved unless you sign in.

If you already have a free Proton account, you’ll automatically get access to the Lumo Free tier, which includes basic encrypted chat history, a limited number of bookmarks and support for small file uploads. It’s available to all Proton users, including those on business plans.

The paid Lumo Plus subscription costs £10.59 a month (or £8.19 if you pay annually). It gives you unlimited chats, longer chat history, the ability to save more favourites and support for uploading bigger or multiple files. It’s also included with Proton’s Visionary plan. That’s cheaper than ChatGPT Plus, Gemini Advanced and Claude Pro, which all cost around £19.99. However, with Lumo’s stricter privacy focus, it might not be as intelligent.

Care about your privacy? Have a read of our round-up of the best VPNs

There’s a new competitor for your AI chatbot of choice, and this one is focused on privacy. Proton, the company behind services like Proton Mail and VPN, has now launched its first AI assistant.

The new chatbot is called Lumo, and it’s designed to focus on privacy above all else. Proton says, “Lumo keeps your conversations confidential and your data fully under your control — never shared, sold, or stolen.”

The company cites how many chatbot users want to talk to services on confidential topics like personal information, health problems, or sometimes even complicated legal documents.

Proton says Lumo is the right chatbot to use to protect your data, even though its features are more limited than alternatives like ChatGPT or Google Gemini. There’s no image generation or voice based search here, but Lumo can do key tasks like searching the web, writing text, analyzing files, and more.

Lumo turns off all web access by default, but you can manually turn it on with a small button at the bottom of the prompt box. It’s easy to then toggle on and off depending on what you’re searching and how much data you’re willing to share online.

Other elements of Proton’s privacy promise include that it will never use your data to train its AI, logs of your chats are deleted (and they’re encrypted during the process), and it won’t ever share your data with any external sources.

There’s also a feature called Ghost mode that allows you to have disappearing chats with Lumo. Use this in a similar way to an incognito mode when you don’t want the browser to follow what you’ve been doing. If you’re a Proton user already, you can also integrate the chatbot directly with its Drive tool to help it read your documents.

Proton Lumo is available on the web as well as through Android and iOS. The app is available now, and it’s free to use for up to 100 messages per a month.

To get unlimited queries, you’ll need to sign up to Lumo Plus for $12.99 a month or $9.99 a month through an annual subscription. If you’re on a Proton Unlimited subscription, you won’t get access to Lumo Plus and you’ll have to pay extra to access. Those on Proton Visionary or Lifetime accounts get access to Lumo Plus without paying extra.

While AI can be helpful, there’s always been the inherent problem of the data generated when we use AI being hoarded by companies like Meta, OpenAI, and more. This often means that any chats you have with the AI — whether Gemini, ChatGPT, or Anthropic’s Claude — could be archived and used to train the AI models further, helping to make them stronger.

While this sounds fine enough on paper, it also means that anything told to the AI chatbot is fair game for the algorithms and machine learning processes to save, break down, and regurgitate elsewhere. This is why you see so many warnings not to share private or identifying information with AI chatbots. AI chatbots just aren’t private, and AI doesn’t go out of its protect your privacy either.

With Lumo, though, Proton says it’s finally giving users a way to benefit from the usefulness of AI without having to sacrifice their data. It’s a point of contention that has made Proton one of the few companies worth keeping an eye on, as the use of end-to-end encryption in everything the company does goes a long way toward helping you feel like your data is secure and safe.