As part of the activities of the Centre for Scientific Information of the Ruđer Bošković Institute in the Horizon 2020 project OpenAIRE Advance, the Croatian Scientific Bibliography - CROSBI has been upgraded and is now aligned with the latest OpenAIRE interoperability guidelines (v. 4.0). With that, CROSBI became the first Croatian data infrastructure at the highest level aligned with the prescribed guidelines, and the records from CROSBI are now also available through OpenAIRE Explore. As part of the OpenAIRE guidelines, the publicly available OAI-PMH database is implemented in CROSBI, through which metadata records can be collected in accordance with the defined guidelines.