Mark Dingemanse

Proton released an "AI" (Lumo) that they market as open source. About that... with zero openness features checked it is the least open "open" model ever to arrive in the European OS AI index

Compare Lumo, Deepseek and OLMo: https://osai-index.eu/compare?models=OLMo,deepseek-v3,lumo

Until Proton tells us more about the base LLM and other aspects of this system, it is officially the least open LLM that is marketed as "open source"

#opensource #genAI #Proton #openwashing

Aug 29, 2025 at 12:02pmWeb
Show threadAndy PiperAug 29, 2025
@dingemansemark I had a quick look (and I also tried asking Lumo) and so far as I understand it, Lumo itself routes between models from Mistral, Olmo and OpenHands; the front-end code for their iOS and Android apps is on GitHub, and the web code confusingly appears to be in one of the ProtonMail repos. Via https://proton.me/community/open-source, and a query to the Lumo chat itself. Not affiliated with Proton myself, although I am a customer of their VPN and Mail services, YMMV.
An open source privacy company | Proton

All our apps (Proton Mail, Proton Drive, etc) are open source and independently audited. Anyone can inspect our software and confirm our encryption works.

Proton
Show threadMark DingemanseAug 30, 2025
@andypiper that's as far as we got too — at this point, Proton has not provided any documentation of this system despite touting its 'open source' status in three different places. It is most likely that it's three models in a trenchcoat, could even be tapping into a big tech LLM API under the hood; point is, we would know if it were truly open source https://osai-index.eu/news/lumo-proton-least-open
Lumo: the least open 'open' AI assistant | European Open Source AI Index

Proton sets a new record in open-washing

European Open Source AI Index