AI Potluck
Product / UX / UI & API

Proton Lumo

Proton

Privacy-focused AI assistant from Proton with zero-access encryption, a no-logs policy and a ghost mode that discards conversations on close. It runs open-weights models in Proton's European data centers rather than sending prompts to third-party providers, and requires no account.

Proton's own account of Lumo's openness and the axis's reading differ in scope, so the axis carries the evidence. Verified 2026-08-13 via the ProtonLumo iOS client repository and Proton's Lumo announcements.

Openness

2 high confidence
2.0
source
partial(GPLv3 clients only
clients
open(GPLv3 - web in ProtonMail/WebClients, iOS/Android in ProtonLumo)
service
closed(backend, routing, model-serving not public)
license
GPLv3(clients)

Open clients (GPLv3) over a proprietary hosted service: the backend, routing and model-serving layer are not published. It is marketed as "fully open source", but support pages and third-party reviews note that only the clients are open. A published client standing in for an unpublished engine makes the source partial rather than public, which scores as source-available; open core would mean an OSI-licensed core with a paid tier withheld, which this is not. The published iOS client is a SwiftUI shell around a web view pointed at lumo.proton.me, with native payment and speech handling - exactly that split, a client published and the service behind it not. The European Open Source AI Index reaches the same conclusion independently.

Adoption

3 medium confidence
3.0

Launched in July 2025 with Lumo 1.1 following, distributed across Proton's large account base of 100M+ accounts and available on web, iOS and Android with no account required. No Lumo-specific usage numbers are disclosed, so the level rests on that reported reach rather than a measured count.

Capability

3 medium confidence
3.0

Capable privacy assistant with file upload, web search, and a reasoning mode, but confined to open-weight models and the Proton ecosystem; lighter on multimodal/plugins than frontier consumer apps. Mid-tier on the chat-UI feature matrix.

Verified 2026-08-13