Proton Lumo
A single roll-up of ownership and CLOUD Act exposure.
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EU-Sovereign EU/EEA/Switzerland-owned and -operated, with no identified CLOUD Act exposure.
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EU-Based This listing EU-operated, with at most minor or transient US exposure.
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EU-Hosted EU hosting available, but a US parent or hyperscaler sub-processor creates material exposure.
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US-Linked Operated by a US-incorporated entity, directly subject to US jurisdiction.
Proton AG (UID CHE-354.686.492, Plan-les-Ouates, Geneva, Switzerland); primary shareholder the Swiss non-profit Proton Foundation (CHE-418.863.304); EU GDPR representative Proton Europe sàrl, Luxembourg
AI assistant from Swiss Proton AG: open-weight models on Proton-run servers in Europe, zero-access encrypted chat history, no training on chats; inbound traffic is routed via Cloudflare's network.
Proton Lumo is a European service hosted in Germany, with at most minor, transient US exposure under the CLOUD Act. It is listed under Sovereign AI.
Assessment notes
Lumo is operated by Proton AG (CHE-354.686.492, Plan-les-Ouates, Geneva), whose primary shareholder is the Swiss non-profit Proton Foundation; there is no US parent, and Proton states that it has no venture-capital investors. The app encrypts each prompt to a key held only by the LLM servers, requests are processed in memory without logs, and saved chats are kept with zero-access encryption; the Lumo terms say content is not used to maintain, develop or improve the service, and the only training path is opt-in, anonymised feedback on the Apertus model, shared with ETH Zurich and EPFL. Inference runs on open-weight models on servers Proton controls: Proton moved Lumo out of Switzerland at launch in July 2025, naming Germany with Norway in preparation, and its August 2026 incident report describes Frankfurt as the main data centre with Zurich as failover. A public DPA (February 2026) covers Proton services, and the Lumo privacy policy lists only ancillary third-party processors (Zendesk, Stripe, PayPal, Chargebee and Atlassian, for support and payments). Two findings hold the score at 4 rather than 5. Every Proton IP range observed at audit, including the one serving lumo.proton.me and its API, is announced to the internet solely through Cloudflare (AS13335), a network-layer arrangement typically used for DDoS protection that Proton's processor lists do not name; TLS still terminates on Proton's own servers and prompts carry the extra encryption layer, so Cloudflare handles ciphertext and connection metadata. And optional web search sends a simplified version of the query to "selected partner APIs" that Proton does not name. CLOUD Act exposure is therefore minor: transient US network transit, with no US-owned infrastructure storing or processing chat content. Proton AG holds ISO 27001 (May 2024) and a SOC 2 Type II attestation (July 2025, audited by Schellman); both predate Lumo's launch, and the published material does not say whether Lumo is in scope.
Findings
- CLOUD Act
- CLOUD Act exposure
How exposed customer data is to US authorities under the CLOUD Act (Clarifying Lawful Overseas Use of Data Act).
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None EU operator, no US parent, no US sub-processors of note.
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Minor This listing A transient US sub-processor (CDN, maps); data at rest stays in the EU.
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Material US parent, or a core sub-processor is a US-owned hyperscaler.
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Direct The operator itself is US-incorporated.
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- Ownership
- Ownership
Where ultimate control over the operating company sits.
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EU-owned EU-incorporated and EU-controlled; no significant US ownership.
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European This listing Swiss/EEA-owned, with no significant US ownership; treated as European.
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EU HQ, US-funded EU-headquartered but US venture- or PE-controlled.
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US-owned US-headquartered, or has a US parent company.
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- Sub-processors
- 0 none disclosed
Verified signals
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EU / adequacy hosting: Yes
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EU / adequacy operator: Yes
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No US CLOUD Act exposure: Not assessed
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Public DPA: Yes
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Sub-processors disclosed: Yes
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Open-source clients: No
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Third-party certification: Yes
Jump to
About Proton Lumo
Lumo is the AI assistant of Proton AG, the Geneva company behind Proton Mail. It launched in July 2025 and was rebuilt as Lumo 2.0 in June 2026, on the web at lumo.proton.me and in Android and iOS apps. Users pick Lumo 2.0 Lite, Lumo 2.0 Max or Apertus 1.5, the fully open model of the Swiss AI Initiative (EPFL, ETH Zurich, CSCS), in a fast or a thinking mode. Proton names the open-weight models behind the service as Qwen 3.5, GLM 5.3, Image-Turbo, FireRed-Image-Edit-1.1 and Apertus 1.5; Qwen and GLM are developed in China by Alibaba and Zhipu AI, and the weights run on Proton's hardware, so prompts do not reach their developers. Lumo 2.0 added image analysis, generation and editing, memory and a stronger web search with cited sources, alongside the existing encrypted Projects. Guests can chat without an account, the free plan has daily limits, and Lumo Plus costs €12.99 per month or €9.99 per month billed annually. Lumo Professional for teams adds admin tools. There is no public API.
The app encrypts each prompt to a key that only the LLM servers hold, so Proton's internal systems forward ciphertext; the model answers in memory without logs, and saved chats, files and memories use zero-access encryption that Proton cannot read. The terms say content is not used to improve the service; the only training path is opt-in, anonymised feedback on Apertus answers, shared with ETH Zurich and EPFL. The web and mobile clients are open source under GPL-3.0, while the server code and model routing are not published. Proton moved Lumo out of Switzerland at launch, citing a proposed Swiss surveillance ordinance, and names Germany as its location; an August 2026 incident report calls Frankfurt the main data centre, so hosting is recorded as Germany, with the operator in Switzerland.
Ownership is recorded as Other, the tier for Swiss operators: the primary shareholder is the non-profit Proton Foundation, with no US parent. A public DPA covers Proton services, and the Lumo privacy policy names only support and payment processors. CLOUD Act exposure is Minor because of two findings at audit. All of Proton's IP ranges, including Lumo's, reach the internet only through Cloudflare's network, a setup Proton's processor lists do not mention; TLS still ends on Proton's servers, so Cloudflare carries ciphertext and connection metadata. Optional web search also sends a simplified query to search partners Proton does not name. Best fit: people and teams who want a capable assistant for confidential work without logging or training on their chats.
Sub-processor map · none disclosed
Frameworks & certifications
Capability matrix
Table 1Capabilities of Proton Lumo
Integration & access
Compliance & governance
Pricing & tiers
Public documents
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GermanyEU-HostedCLOUD Act exposure
How exposed customer data is to US authorities under the CLOUD Act (Clarifying Lawful Overseas Use of Data Act).
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None EU operator, no US parent, no US sub-processors of note.
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Minor A transient US sub-processor (CDN, maps); data at rest stays in the EU.
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Material This listing US parent, or a core sub-processor is a US-owned hyperscaler.
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Direct The operator itself is US-incorporated.
Public DPA: No Sub-processors: No Open source: No -
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GermanyEU-HostedCLOUD Act exposure
How exposed customer data is to US authorities under the CLOUD Act (Clarifying Lawful Overseas Use of Data Act).
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None EU operator, no US parent, no US sub-processors of note.
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Minor A transient US sub-processor (CDN, maps); data at rest stays in the EU.
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Material This listing US parent, or a core sub-processor is a US-owned hyperscaler.
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Direct The operator itself is US-incorporated.
Public DPA: No Sub-processors: No Open source: Yes -
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Germany · €7.49/moEU-HostedCLOUD Act exposure
How exposed customer data is to US authorities under the CLOUD Act (Clarifying Lawful Overseas Use of Data Act).
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None EU operator, no US parent, no US sub-processors of note.
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Minor A transient US sub-processor (CDN, maps); data at rest stays in the EU.
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Material This listing US parent, or a core sub-processor is a US-owned hyperscaler.
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Direct The operator itself is US-incorporated.
Public DPA: Not assessed Sub-processors: No Open source: No -
| Product | Sovereignty | CLOUD Act | Signals | From |
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| Aleph Alpha Germany | EU-Hosted | CLOUD Act exposure
How exposed customer data is to US authorities under the CLOUD Act (Clarifying Lawful Overseas Use of Data Act).
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Public DPA: No
Sub-processors: No
Open source: No
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— |
| Black Forest Labs Germany | EU-Hosted | CLOUD Act exposure
How exposed customer data is to US authorities under the CLOUD Act (Clarifying Lawful Overseas Use of Data Act).
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Public DPA: No
Sub-processors: No
Open source: Yes
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| DeepL Germany | EU-Hosted | CLOUD Act exposure
How exposed customer data is to US authorities under the CLOUD Act (Clarifying Lawful Overseas Use of Data Act).
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Public DPA: Not assessed
Sub-processors: No
Open source: No
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€7.49/mo |