In my thesis I demonstrate some parking assist systems in the world, and present my concept which is designed to find free spaces on the streets. First I introduce the implemented solutions so far and I also demonstrate the advantages of the vehicle-to-vehicle communication and the OBD- II car diagnostics. Based on these topics I planned and created my Smart Parking Assist application and a back-end system to support its functionalities. In my essay I highlighted the logical connections between the components and the utilized technologies. During the development my goal was to achieve simplicity and usefulness. To find free spaces the driver only need to give the address of the target and the maximum distance from it. If the results are returned to the application, the user can choose from a list of streets according to the distance and the number of the free spaces. The core of the system is a database derived from the Hungarian atlas of OpenStreetMap. This data bank is accessible via a Java Servlet which is responsible for the request handling. It can reach the database and return the asked information. The number of free spaces in a street are estimated by the state of the users. To facilitate this process, the application can supervise automatically the parking state by an OBD-II device. According to this feature the smartphone can indicate the parking position to the server side. I would like to emphasize that my system is only a concept and the application was never released. But my thesis also covers some improvements, where I summarize the needed steps to be able to operate in real life too.