Proton, the Swiss company best known for encrypted services like Proton Mail and Proton VPN, has launched its first AI chatbot, Lumo – a tool designed to compete with mainstream AI assistants while prioritising privacy and user control.
Unlike tools such as ChatGPT, Gemini, or Claude, which often log user interactions and use them to train large language models (LLMs), Lumo is built around a “zero-logs” architecture.
Proton says user data is encrypted end-to-end, never stored on its servers, and never used for training or profiling.
“When we first launched Proton Mail a decade ago, our vision was to build a better alternative to Big Tech ecosystems for the benefit of all of society,” said Andy Yen, Founder and CEO of Proton.
Big Tech is using AI to supercharge the collection of sensitive user data to accelerate the world’s transition to surveillance capitalism. For this reason, we believe it is essential to provide an alternative that protects privacy and serves users as opposed to exploiting them.”
Privacy by Design?
Conversations are not recorded server-side, and any chat history users do choose to save is encrypted such that even Proton cannot read it.
The chatbot also supports a “ghost mode,” where sessions disappear entirely once closed.
Key privacy features include:
- No data logging – chats are not stored on Proton’s servers by default
- Zero-access encryption – stored data is readable only on the user’s devices
- No training on user data – user input is not used to refine the model
- No third-party data sharing – no advertisers or partners receive data
These measures differentiate Lumo from most other AI assistants, which typically reserve the right to use user inputs for model improvement and analytics – a practice that has drawn increasing scrutiny.
Functionality and Limitations
Lumo supports many of the same features as its competitors: document summarisation, email writing, code assistance, and even file uploads.
Optional web search is available, but turned off by default to minimise data exposure.
It integrates with other Proton services, such as Proton Drive, allowing users to analyse encrypted files.
However, there is currently limited information on how its performance compares with more established AI models from OpenAI or Google, especially in terms of reasoning ability, factual accuracy, or multimodal support.
Unlike ChatGPT or Gemini, Lumo is based on open-source language models, although Proton has not yet disclosed which models are in use or how they’ve been fine-tuned.
AI Assistant Feature Comparison
| Feature / Criteria | Lumo | ChatGPT | Gemini | Claude |
|---|---|---|---|---|
| Privacy Model | Built for privacy by design | Data may be logged and reused | Integrated with broader account ecosystem | Claims privacy protections; less transparent |
| Data Logging | No server-side logs | Yes, unless disabled manually | Yes | Some logging; not clearly defined |
| Used for Model Training | No | Yes, opt-out available | Yes, may use user input | Yes, under certain conditions |
| End-to-End Encryption | Yes, zero-access | No | No | No |
| Ephemeral / Ghost Mode | Yes | No | No | Limited |
| Open Source Components | Yes (open models used) | No | No | Partial or unclear |
| File Upload & Analysis | Yes, not stored | Yes, stored temporarily | Yes | Yes |
| Web Search Capability | Optional, off by default | Yes (enabled by default in Plus) | Yes | Limited or in beta |
| Free Tier | Yes | Yes (with limitations) | Yes (with limitations) | Yes (limited model access) |
| Premium Tier | $12.99/month | $20/month | $19.99/month | $20/month |
| Jurisdiction | European Union | United States | United States | United States |
| Third-Party Data Sharing | No | Possible via APIs and partners | Yes (ad/analytics ecosystem) | Not clearly defined |
Business Model and Access
Lumo is free to use – even without a Proton account – though logging in allows access to encrypted chat history across devices.
A paid tier, Lumo Plus, is available for $12.99/month, offering extended chat history, file upload capabilities, and more usage.
Notably, Proton is not using advertising to fund the service. Instead, it focuses on its subscription-based model, which the company argues aligns better with user privacy and transparency.
In parallel with Lumo’s launch, Proton announced a broader move to relocate much of its infrastructure from Switzerland to the European Union, citing concerns over proposed Swiss surveillance laws.
The company says this shift will involve over €100 million in investment to strengthen European technological sovereignty and reduce dependence on U.S. and Chinese platforms.
What This Means For IT Leaders
Lumo arrives at a moment when concerns about AI data privacy are growing, particularly among professionals handling sensitive information.
While many users have become comfortable with mainstream chatbots, Proton is betting that a subset – including legal and medical users – will value confidentiality over convenience.
However, Lumo still faces major challenges: its capabilities remain untested against leading models in terms of quality and versatility.
Whether Proton can keep up with the rapid pace of AI development while maintaining its strict privacy commitments is unclear.
Still, Lumo represents a notable attempt to reshape what AI can look like in a post-GDPR, post-privacy-fatigue world – one where trust, not just intelligence, becomes the key differentiator.
