Apertus 1.5: Pioneering Next-Gen Open AI Systems

Trained on the Alps supercomputer at CSCS in Lugano, Apertus is one of the world's largest fully open language models, providing transparency into its training data, code and development process. It allows researchers, public institutions and companies to inspect, adapt and improve the model for their own needs.

A long-term vision for sovereign AI

The release of Apertus 1.5 marks another step towards a long-term goal: building a sovereign AI infrastructure that provides an open alternative to proprietary commercial models. Over the coming years, the Apertus team plans to release regular model updates with steadily expanding capabilities for research, education, public administration and industry.

The project is led by Dr. Imanol Schlag, research scientist at ETH Zurich and Professors Martin Jaggi and Antoine Bosselut from EPFL's school of computer and communication sciences.

"Rather than introducing an entirely new model, Apertus 1.5 incorporates feedback from the first release and adds several new capabilities", explains Jaggi. Most notably, the model can now understand images and audio alongside text, opening the door to a broader range of applications. It also offers improved reasoning, stronger instruction following and better support for tool use.

"Apertus is not about competing with frontier models from private companies, but about providing trustworthy, transparent AI that organizations big and small can build upon with confidence", says Schlag."With every release, this foundation becomes more capable."

Growing adaptation across sectors

The first release of Apertus has already enabled a growing range of applications. In the Canton of Ticino, it powers an in-house AI translation service, allowing sensitive government documents to be translated without relying on commercial providers. Researchers at EPFL have used Apertus as one of the foundation models for MeditronFO, the world's first fully open framework for building medical large language models.

Apertus is also being used in journalism. The Basel-based online news outlet Bajour runs the locally hosted model in its newsroom to prepare local political news for its daily Basel Briefing newsletter. The team has also developed a search and analysis tool based on Apertus that allows journalists to explore years of cantonal parliament transcripts, trace politicians' positions over time and identify inconsistencies between past statements and later actions, uncovering stories that would otherwise take days of manual research.

"As journalists, we value transparency and openness," says Samuel Hufschmid, editor at Bajour. "With Apertus, we know what we're building on. Its open-source nature and transparency make it a natural fit for our newsroom." The tools developed at Bajour are also being made available to other news organizations through the publishing ecosystem We.Publish.

The release of Apertus 1.5 and the Apertus mini suite is part of a broader roadmap that will see increasingly capable versions become available over the coming years, providing an open source foundation for AI in Switzerland and beyond.