Apertus: An Open, Multilingual LLM for a Transparent AI Future

The New Swiss AI Flagship

Apertus is the first large language model from Switzerland, developed by Swiss-AI with a focus on precision, multilingualism, and European values. Now exclusively available on our AI platform.

Two Model Variants for Every Need

Apertus 70B

The flagship model with 70 billion parameters offers:

• Highest precision for complex tasks
• Advanced reasoning capabilities
• Optimized for demanding business applications
• Multilingual proficiency (German, French, Italian, English)

Apertus 8B

The efficient model with 8 billion parameters:

• Fast response times
• Cost-effective operation
• Ideal for real-time applications
• Perfect for standardized tasks

Background: The Development of Apertus

A Milestone in Swiss AI Research

Researchers from EPFL, ETH Zurich, and CSCS have developed Apertus, a fully open Large Language Model (LLM)—one of the largest of its kind. As a foundational technology, Apertus enables innovation and strengthens AI expertise across research, society, and industry by allowing others to build upon it.

Apertus is currently available through strategic partner Swisscom, the AI platform Hugging Face, and the Public AI network.

Swiss Quality Meets Innovation

• 100% GDPR compliant: Fully hosted in Switzerland
• Data sovereignty: Your data stays in Europe
• Transparency: Open-source based and traceable
• Multilingual: Native support for all Swiss national languages

The Initiative

In July, EPFL, ETH Zurich, and CSCS announced their joint initiative to build a large language model (LLM). Now, this model is available and serves as a building block for developers and organizations for future applications such as chatbots, translation systems, or educational tools.

The model is named Apertus—Latin for “open”—highlighting its characteristic feature: The entire development process, including its architecture, model weights, and training data and recipes, is openly accessible and fully documented.

Fully Open-Source

As a fully open language model, Apertus allows researchers, professionals, and enthusiasts to build on the model and adapt it to their specific needs, as well as inspect every part of the training process. This distinguishes Apertus from models that only make selected components accessible.

“With this release, we want to provide a blueprint for how a trustworthy, sovereign, and inclusive AI model can be developed,” says Martin Jaggi, Professor of Machine Learning at EPFL and a member of the steering committee of the Swiss AI Initiative.

Technical Highlights

• Fine-tuning on European datasets
• Optimized for the Swiss context and culture
• Advanced security features
• API compatible with common standards
• Seamless integration into existing systems

Driver for Innovation

With their open approach, EPFL, ETH Zurich, and CSCS are breaking new ground. “Apertus is not a conventional case of technology transfer from research to product. Instead, we see it as a driver of innovation and a means of strengthening AI expertise in research, society, and industry,” says Thomas Schulthess, Director of CSCS and Professor at ETH Zurich.

Application Areas

• Document Analysis: Processing and summarizing complex documents
• Code Generation: Support for software development
• Creative Content: Highest quality text generation
• Data Analysis: Insights from structured and unstructured data
• Customer Service: Intelligent chatbots and support systems

Multilingualism as Core

Trained on 15 trillion tokens in more than 1,000 languages—40% of the data is non-English—Apertus includes many languages that were previously underrepresented in LLMs, such as Swiss German, Romansh, and many others.

“Apertus is built for the common good. It is one of the few fully open LLMs of this magnitude and the first of its kind to embody multilingualism, transparency, and compliance as fundamental design principles,” says Imanol Schlag, technical lead of the LLM project and research scientist at ETH Zurich.

Partnership with Swisscom

“Swisscom is proud to be among the first to deploy this pioneering large language model on our sovereign Swiss AI Platform. As a strategic partner of the Swiss AI Initiative, we support access to Apertus during the Swiss {ai} Weeks. This underscores our commitment to shaping a secure and responsible AI ecosystem that serves the public interest and strengthens Switzerland’s digital sovereignty,” comments Daniel Dobos, Research Director at Swisscom.

Accessibility and Availability

While setting up Apertus is straightforward for professionals and savvy users, practical use requires additional components such as servers, cloud infrastructure, or specific user interfaces. The upcoming Swiss {ai} Weeks will be the first opportunity for developers to experiment hands-on with Apertus, test its capabilities, and provide feedback for improvements to future versions.

Transparency and Compliance

Apertus is designed with transparency at its core, ensuring the complete reproducibility of the training process. In addition to the models, the research team has released a set of resources: comprehensive documentation and source code of the training process and the datasets used, model weights including intermediate checkpoints—all published under a permissive open-source license that also allows for commercial use.

Apertus was developed with due consideration of Swiss data protection laws, Swiss copyright law, and the transparency obligations under the EU AI Act. Special attention was paid to data integrity and ethical standards: The training corpus is based only on publicly available data.

The Beginning of a Journey

“Apertus shows that generative AI can be both powerful and open,” says Antoine Bosselut, Professor and Head of the Natural Language Processing Laboratory at EPFL and co-leader of the Swiss AI Initiative. “The release of Apertus is not a final step, but the beginning of a journey, a long-term commitment to open, trustworthy, and sovereign AI foundations for the global common good.”

Future versions aim to expand the model family, improve efficiency, and explore domain-specific adaptations in fields such as law, climate, health, and education.

Pricing Models

Transparent and fair pricing:

• Pay-per-use without hidden costs
• Volume discounts for companies
• Free trial period available
• Individual enterprise packages

Test Now

Experience the future of Swiss AI. Register for a free trial today and discover the possibilities of Apertus.