Today's era is characterized by numerous and widely available contents and services that we use every day in all segments of life. Most of such services are based precisely on digital technologies and their implementation in everyday life. It is unquestionable that human life is changing, modernizing day by day. In such circumstances, one gets the impression that activities such as reading books and going to the library are slowly being forgotten. For this reason, public libraries in the digital age must adapt to new needs and trends, both in society and among their users. With modern technologies and digitized content, it tries to get closer to today's modern user. Libraries of the city of Zagreb, as the largest network of libraries in the Republic of Croatia, keep up with the times and increasingly develop their digital services. One of the newest is the eZaki application, which allows members of the libraries of the city of Zagreb to have access to the services of their library at any time. The aforementioned application is also the first application in the Republic of Croatia intended for the described services and is therefore the subject of this work. This thesis presents the results of research on the use of the application by members, their opinions and satisfaction with use. It is to be expected that each individual application has its advantages and disadvantages. The data obtained from the research will give a better insight into the further development of the eZaki application and digital services in libraries in general.