Digital repositories represent a key infrastructure for the storage and dissemination of scientific and educational content. Their importance increases further in the context of open science and research data management, where repositories are not only expected to have content availability, but also long-term reliability. Such reliability includes technical stability, clearly defined procedures and transparent management of digital objects.

CoreTrustSeal certification is one of the internationally recognized models for assessing the reliability of digital repositories. It is based on a set of 16 criteria that cover the organizational, management and technical aspects of the repository’s work and enable a systematic evaluation of their compliance with the relevant standards.

Repository of the Faculty of Science, University of Zagreb has officially received the CoreTrustSeal certificate of trustworthiness – an international recognition given to a repository that meets high standards of data management, preservation and availability. Faculty of Science, University of Zagreb thus became the first institution in Croatia with this certificate, and its repository is one of only 150 repositories in the world that currently possess it.

Our poster shows the process of obtaining a CoreTrustSeal certificate on the example of the Repository of the Faculty of Science, University of Zagreb. The focus is on the key stages of the procedure, challenges in the preparation of documentation and the effects of certification on the organization and transparency of repository practices.

The development of the repository at Faculty of Science, University of Zagreb took place gradually, from local initiatives to an institutional repository integrated into the national Dabar infrastructure. Such an environment enabled the standardization of work and ensured the technical prerequisites for long-term storage of digital content. Today, the repository includes various types of materials, including student papers, scientific publications and research data, with a high proportion of openly accessible records.

The certification process included self-assessment according to defined criteria, collection and structuring of evidence, and communication with international reviewers. The procedure took place iteratively, through several rounds of evaluation and refinement of documentation, with the aim of a clear and transparent presentation of repository practices.

One of the main challenges was related to the formalization of existing procedures and their systematic documentation. Activities that were already part of daily work needed to be further elaborated, clearly described and linked with appropriate evidence. Additional challenges included harmonizing different sources of information, organizing documentation, and ensuring content comprehensibility in an international context.

The results show that the certification contributed to a clearer definition of responsibilities, improved documentation and increased transparency of the repository’s work. The obtained certificate confirms the repository as a reliable infrastructure for the storage and dissemination of scientific results.
The experience of the Repository of the Faculty of Science, University of Zagreb shows that CoreTrustSeal certification can be successfully implemented within national infrastructure systems, with a clear division of responsibilities and effective cooperation between the institution and the technical service provider.

CoreTrustSeal certification can be seen as a development tool that encourages the systematic improvement of repository practices and contributes to their long-term sustainability in the context of open science.