Lumo

Lumo is an AI chat assistant developed by Proton as a private alternative to mainstream tools like ChatGPT, Gemini, Copilot, and Claude. Its core differentiator is zero-access encryption: conversations can only be decrypted by the user, so Proton has no technical ability to read chats, use them for advertising, or hand them over to third parties, including government requests.

The service is based in Switzerland/EU and operates under GDPR, giving it stronger legal privacy guarantees than many US-based competitors. Lumo's source code is open, allowing independent verification of its privacy claims and confirming that user data isn't fed back into model training.

Functionally, Lumo supports text-to-image generation, real-time web search for up-to-date answers, task and document organization, data and report analysis, and coding or project assistance, including integration with files stored in Proton Drive. A business tier is also available with encrypted team conversations.