Lumo by Proton: an AI assistant built around privacy
Lumo is the chat assistant from Proton, the Swiss company behind Proton Mail and Proton VPN. It is aimed at people who want an everyday chatbot without their conversations being used to train AI models.
Data as of October 22, 2026
Key figures
| Developer | Proton AG |
|---|---|
| Country | Switzerland |
| Launched | July 2025 |
| Free version | Yes, limited |
| Plans | from $12.99 per month |
| Official website | lumo.proton.me |
Features
| Features | |
|---|---|
| Web search | Yes |
| Agent mode | Not disclosed |
| File upload | Yes |
| Image generation | Yes |
| Voice mode | Yes |
| Memory | Not disclosed |
| Code execution | Not disclosed |
| Autonomous browsing | No |
Where to use it
| Where to use it | |
|---|---|
| Web | Yes |
| iPhone | Yes |
| Android | Yes |
| Windows | Not disclosed |
| macOS | Not disclosed |
| Browser extension | Not disclosed |
| French interface | Yes |
| Spanish interface | Yes |
Privacy
| Privacy | |
|---|---|
| Opt out of training on your chats | Yes |
| Temporary chat | Yes |
| EU data residency | Not disclosed |
What Proton is promising
Launched in July 2025, Lumo carries over Proton’s core idea: a European service paid for by subscriptions rather than ads, designed to know as little about you as possible. Proton makes three main commitments. First, your chats are not used to train models; the only exception is anonymized feedback you choose to send about answers from the Apertus 1.5 model. Second, saved history uses zero-access encryption. Third, there are no logs: no timestamps or IP addresses are kept once a request has been handled.
Ghost mode makes the current chat disappear as soon as you close it, and guest sessions are wiped when they end. If you want background on why this matters, see our explainers on GDPR and AI and on how AI assistant memory works.
What you can do with it
Lumo covers the usual jobs of an AI assistant: drafting emails, summarizing documents, rewording text, explaining a topic or reviewing code. It includes built-in AI web search, image generation, file uploads and a Proton Drive connection so it can work with your own documents. The mobile apps add voice dictation, and Projects let you group chats and files around one topic.
One trade-off is worth knowing. Lumo does not use the big proprietary models; it relies on open-weight models such as Qwen and GLM. That is consistent with keeping everything on Proton’s servers, but on complex questions the answers may be less polished than those from the leading labs’ assistants.
Plans and pricing
As of October 22, 2026, Proton’s pricing page lists:
- Free: limited messages and history, limited use of the strongest model, a few image generations, one project.
- Lumo Plus: $12.99 per month, or $9.99 per month billed yearly ($119.88 per year), with more messages and images, unlimited projects and unlimited custom “Lumos”. There is a 30-day money-back guarantee.
Separate business plans are available for teams.
Availability and alternatives
Lumo has no notable regional restrictions for personal use in the US, UK or EU. Proton highlights that it is “built and based in Europe,” on infrastructure it controls. If you are comparing options, Le Chat by Mistral is another European choice, and Duck.ai also focuses on anonymity. Our AI assistants comparison puts them side by side.
Models used
- Qwen 3.5
- GLM 5.3
- Apertus 1.5
- Image-Turbo
- FireRed-Image-Edit-1.1
Strengths
writing · searching with sources
Comparisons
AI assistants
- Alexa+ · Amazon
- Apple Intelligence et Siri AI · Apple
- Brave Leo · Brave Software
- Character.AI · Character Technologies, Inc.
- ChatGPT · OpenAI
- Claude · Anthropic
Frequently asked questions
Is Lumo free to use?
Yes. There is a free plan with no credit card required, and you can even try it as a guest without an account. The free plan caps messages, chat history, image generations and use of the strongest model, and includes one project.
Can Proton read my Lumo chats?
Proton says no. Saved chats are protected with zero-access encryption that only the account holder can unlock. Prompts are encrypted in transit and, according to Proton, erased after processing under a no-logs policy.
Which AI models power Lumo?
Lumo runs open-source models tuned by Proton. As of October 22, 2026, Proton's help page lists Qwen 3.5, GLM 5.3 and Apertus 1.5 for text, plus two image models, all hosted on servers Proton controls.
Does Lumo work outside Europe?
Yes. Lumo is available on the web and in iOS and Android apps, and prices can be shown in US dollars, euros or Swiss francs. Proton stresses that the service is built and run in Europe, which matters to some users for legal reasons.
Data sources
Data as of October 22, 2026
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