Lumo is an AI chat assistant from Proton, the company behind Proton Mail and Proton VPN. Its pitch is that conversations are stored with zero-access encryption, so the company cannot read them, are never used to train AI models, and cannot be shared with advertisers or governments.
Features include web search, the ability to upload small files, linking files and folders through Proton Drive for context, image generation, projects and custom assistants. The code is described as open source, the service is based in Europe and subject to GDPR, and a business edition adds compliance material such as HIPAA, GDPR and ISO 27001 references. Apps exist for iOS and Android.
The free plan needs no credit card and the site says a user can start chatting without creating a Proton account. It has limits on model usage, messages, history and image generations and one project. Lumo Plus raises those limits and adds unlimited projects and custom assistants.
The details on this page come from Lumo’s own website, read on 7 October 2026. Plans, limits and features change, so confirm the current terms on the vendor’s site before you pay.
