The emerging paradigm of data economy can constitute an unmissable and attractive opportunity for companies that aim to consider their data as valuable assets. To fully leverage this opportunity, data owners need to have specific and precise guarantees regarding the protection of data they share from unauthorized access, but also from their misuse. Thus, it becomes crucial to provide mechanisms for secure and trusted data sharing capable of protecting data ownership rights and specifying agreed-upon methods of use. In this sense, data space technology can represent a promising and innovative solution in data management that aims to promote effective and trusted data exchange and sharing. By providing standardized technologies and legal frameworks, data spaces seek to eliminate barriers to data sharing among companies and organizations and, ultimately, fostering the development of innovative value-added services. By promoting interoperability and data sovereignty, data spaces play a crucial role in enhancing collaboration and innovation in the data economy. In this paper, the key European initiatives are collected and organized, with the goal of identifying the most recent advances in the direction of harmonizing the specifications, to facilitate the seamless integration between different solutions and foster secure, flexible and scalable data spaces implementations. The results of this study provide guidelines that can support data space designers in driving the choice of the most proper technical specifications to adopt, among the available open-source solutions.