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Open article · Retrieved 2026-09-18T10:21:31.171050+00:00
# Proton partners with Apertus, Switzerland’s sovereign AI model
- [Proton updates](https://proton.me/blog/proton-updates)
- [Lumo AI](https://proton.me/blog/proton-updates/lumo)
Proton is partnering with the team behind Apertus to bring its new Apertus 1.5 model to Lumo, Proton’s privacy-focused alternative to ChatGPT. The partnership will also give researchers behind Apertus access to real-world feedback that can help them improve it more quickly.
Apertus is a fully open large language model developed by researchers at [EPFL(new window)](https://actu.epfl.ch/news/apertus-s-associe-a-lumo-l-assistant-ia-de-proton/), [ETH Zurich(new window)](https://ethz.ch/de/news-und-veranstaltungen/eth-news/news/2026/09/apertus-arbeitet-neu-mit-dem-ki-assistenten-lumo-von-proton-zusammen.html), and the Swiss National Supercomputing Centre (CSCS). Its architecture, training data, and methods are open, and it’s trained on publicly available data, respecting opt-out requests and filtering out personal details. It fills an important role in today’s AI landscape by providing a fully open source model with a transparent and reproducible training pipeline. In a world dominated by US and Chinese models, Apertus is instrumental in Europe’s tech sovereignty.
The world’s leading AI models have millions of people using them every day, creating real-world feedback loops that help make them better. Fully open models developed in an academic context do not have access to feedback at the same scale, limiting their ability to compete at the frontier.
With this partnership, that could start to change. Proton is introducing a feedback mechanism that connects people using Apertus in Lumo with the researchers building it. Tens of millions of Lumo users around the world can now choose to contribute feedback, helping independent, ethical, and truly open source AI become more competitive.
## Building a European alternative
Europe now has the pieces of an independent AI stack: infrastructure it controls, a model open by design, and a product that puts it directly in people’s hands.
“We don’t want to spend the next decade relying on other countries for the AI we use every day,” said Eamonn Maguire, Director of AI at Proton. “Having our own AI isn’t enough. It needs to be competitive so that people actually use it. This partnership with the Swiss AI Initiative gives Europe a path to get there.”
One of the biggest advantages leading AI labs have is a constant stream of feedback from millions of people using their models. Bringing Apertus to Lumo gives the university research teams behind it access to this feedback at scale, helping level the playing field.
## Apertus in Lumo today
To start using Apertus in Lumo, select Apertus 1.5 from the model dropdown, and start chatting as normal. Like other conversations in Lumo, your chats are protected by zero-access encryption and stay private by default.
If you choose to give feedback on an Apertus response, tap the thumbs-up or thumbs-down button to send in your feedback. Your contribution will be anonymized, and made available to the university research teams behind Apertus.
“Real-world feedback is the one ingredient that open models have been missing. Thanks to Proton, Lumo users will be able to voluntarily provide feedback that contributes to Apertus research. For a fully open, publicly developed model, that is a game changer,” says Imanol Schlag, Research Scientist at the ETH AI Center and co-lead of the Apertus project.
“Making Apertus available in Lumo gives us valuable insights into how the model performs in real-world settings. Voluntary feedback also helps us identify where it can be made more useful and more robust,” says Martin Jaggi, Professor at EPFL and co-lead of the Apertus project. “It also means that we are enabling a broader community to contribute to the model’s further improvement.”
## Why work together
Building an open and independent AI ecosystem is bigger than any one model or company. To compete in AI, Europe needs to pool its resources and build public-private partnerships that can do what no single organization can achieve alone. Europe’s future in AI depends on researchers building in the open, infrastructure governed in Europe, companies turning that technology into products people can use, and people willing to help those technologies improve.
Through this partnership, we are taking steps to make that alternative more than an idea. Starting today, fully open source AI is now something people can use and — if and when they choose to — help shape for the future.
[Try Lumo now(new window)](https://lumo.proton.me/)