Most AI assistants are built on a familiar arrangement: you get useful tools, the company gets your data. Lumo, launched by Swiss privacy company Proton in July 2025, refuses that deal entirely. Every conversation is protected by zero-access encryption, no logs are kept server-side, and your chats are never used to train the underlying models.
Lumo runs on a set of open-source large language models, including Mistral Small 3, OLMO 2 32B, and OpenHands 32B, with a routing layer that sends each query to the most appropriate model for the task. The client-side code is open source on GitHub and open to independent review. TIME named Lumo a Best Inventions 2025 special mention, recognizing the broader privacy architecture rather than raw AI performance.
