About Apertus
Apertus is Switzerland’s first large-scale, fully open, multilingual language model. Developed by researchers at ETH Zurich, EPFL, and the Swiss National Supercomputing Centre (CSCS), it represents a new approach to foundation model development: built by public institutions, designed for the public good.
The name comes from the Latin word for “open”, reflecting the model’s defining characteristic. Unlike commercial models developed behind closed doors, Apertus makes its architecture, weights, training data, and methods fully accessible.
Learn more about the Apertus Roadmap and Swiss AI Initiative in the following sections.
Roadmap
- Fully open: architecture, weights, training data, and methods all public, released under the Apache 2.0 licence, which allows commercial use.
- Dense 8B and 70B models, among the largest fully open models available, with the 8B among the best dense models at the 8-10B scale.
- Pretrained on over 1000 languages, using only data from public, versioned sources under open licences, with opt-outs respected for web data and a published, peer-reviewed mechanism that effectively prevents memorisation of training data.
- Instruction following, aligned to the open values of the Apertus Charter.
Distillation of Apertus into 0.5B, 1.5B, and 4B models for mobile and browser deployment: competitive performance at a fraction of the training cost.
A continuation of Apertus 1.0, and among the best fully open models at this scale for following instructions. Adds image understanding competitive with leading open-weight models at this scale, audio understanding, stronger tool use, and reasoning capability from our second-generation post-training pipeline. Stronger adherence to the Apertus Charter.
A magnitude larger model, developed to the same standard of transparency and trustworthiness: multimodal understanding, a more globally fair vocabulary, and more.
Further development based on feedback from our partners and developers.
Planned dates are targets and may shift.
Please visit the Frequently Asked Questions and our Documentation section for details. Use the Contact page to share ideas and questions with the Apertus team.
Swiss AI Initiative
The Swiss AI Initiative is a national research effort to build capabilities for advanced, trustworthy AI systems for the benefit of society. Launched in December 2023, it is co-led by ETH Zurich and EPFL. Apertus is one of several projects within the Initiative, which spans research in foundation models, AI safety, applications, and education.
The Initiative represents one of the world’s largest open science efforts dedicated to AI foundation models. It pursues an open science approach to increase transparency and access for startups, SMEs, large companies, and the public sector in Switzerland and beyond. Please visit swiss-ai.org to learn more.
We are grateful for the support of all our strategic partners, members, and community.