What is Lumo?
Lumo is Proton's privacy-first AI assistant that chats, searches the web and works with files while keeping chats encrypted. It comes from Proton AG, the Swiss company behind Proton Mail and Proton VPN, and launched in 2025. Chats are stored with zero-access encryption, so Proton says even it cannot read them, conversations are not logged on servers, and data is never used to train models. Lumo runs on the web, iOS and Android, and was named one of TIME's Best Inventions of 2025.
Lumo's difference is trust rather than raw model power. Its code is open source, it is based in Europe under GDPR, and it does not share data with advertisers or third parties. Beyond chat, it offers web search, image generation, file uploads from Proton Drive and Projects for organising work. It suits people who want help drafting emails, summarising documents, researching topics or brainstorming without handing their data to an ad-funded company.
Main Features
- Chat with an AI assistant whose history is stored with zero-access encryption.
- Search the web for current information inside a conversation.
- Upload files or attach documents from Proton Drive for analysis.
- Generate images from text prompts.
- Organise chats and files into Projects and create custom Lumos.
- Use guest mode without an account, including over Tor.
- Verify how it works through its open-source code.
How to Get Started with Lumo
- Open lumo.proton.me or install the Lumo app on iOS or Android.
- Use guest mode or sign in with a free Proton account to save chats.
- Turn on web search or upload a file when you need it.
- Upgrade to Lumo Plus for unlimited chats and more advanced model usage.
Lumo Pricing
The Free plan includes limited messages, chat history, image generations and 1 Project. Lumo Plus costs about $12.99 per month or $9.99 per month billed yearly and adds unlimited chats, history, image generations and Projects plus more use of the advanced model. Lumo Plus has a 30-day money-back guarantee and is also included in some Proton bundles.
Who Should Use It?
- Privacy-conscious people who avoid mainstream AI chatbots.
- Proton Mail and Proton Drive users who want AI in the same ecosystem.
- Journalists, lawyers and others handling sensitive information.
- European users who prefer a GDPR-based provider.
- Anyone who wants to try private AI chat without an account.
Lumo Alternatives
- Duck.ai: free private chat with several models
- Le Chat by Mistral: European assistant with more features and agents
- ChatGPT: more powerful features if privacy is less important
Frequently Asked Questions
Is Lumo free?
Yes, Lumo has a free plan with limited usage. Lumo Plus costs about $12.99 per month, or $9.99 per month billed yearly.
Is Lumo private?
Yes. Proton says Lumo keeps no conversation logs, stores chats with zero-access encryption and never trains models on your data.
What AI model does Lumo use?
Lumo runs on open-source large language models hosted in Proton's European data centers, and Proton publishes the app code for review.
Lumo vs ChatGPT: which is better?
ChatGPT has more features and stronger models, while Lumo is better if privacy and data control matter most.