In recent years, sustainability as a concept has become the subject of several scientific debates. Along with the smart city trend, emphasis is also being placed on the sustainability of cities and towns, yet there is a research gap for smaller municipalities where there is no current scope for increasing the level of digitization or implementing smart city practices. Sustainability here has to be achieved differently, in particular through communication and transparency. This issue is addressed in the present research, which examines 116 Slovak municipalities, as well as their strategic documents and online communication with citizens, using a content analysis method. The study aims to provide knowledge about the functioning of online communication in Slovak local governments by answering seven research questions. These are linked to two research hypotheses, which are also evaluated using a statistical test. One of the main findings is that the overall sustainability work in a local government is dependent on its size. Thus, larger local governments are more likely to implement sustainability. It was also found that larger villages and towns use term sustainability more actively in their strategies than the smaller ones. Additionally, more information channels do not always mean better informing about plans and strategies connected to sustainability in local governments. This paper presents the findings from our research, which can contribute to the field of local government research and management by broadening the view on smaller villages and their functioning in terms of online communication with inhabitants. [ABSTRACT FROM AUTHOR]