Apertus is an open source Large Language Model (LLM) developed in Switzerland. This documentation shows you how to get started with the LLM, whether as user, researcher, or advanced contributor: we are maintaining this knowledge base for you, and could ✉️ use your feedback.

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About the project

The model development team is part of the Swiss AI Initiative, which started in late 2023. This is a platform for over 80 data science projects including the LLM development. Key highlights of the LLM project, as announced in July, include:

  • Multilingualism: Trained on more than 15 trillion tokens across 1,500+ languages, 40% non-English - equal usage cost across languages - see @epfml
  • Performance: This is a large model (8 billion and 70 billion parameters), trained on a lot of tokens, and it will be continue to be actively optimized.
  • Open & Transparent: Published under Apache-2.0 license - including source code, weights, and open training data.
  • Data Privacy: Compliant with GDPR, EU AI Act, and Swiss data protection laws - see Fan et al 2025
  • Infrastructure: Developed on the new Alps supercomputer at CSCS with over 10,000 NVIDIA GH200 Grace-Hopper chips
  • Global Reach: Research and borderless applications in mind, for sovereign and international public-interest AI.

Sources

For further information: