The project was performed in collaboration with the company Prevas AB. The aim of the project was to implement a GPS tracking device, or a GPS tracker, that has a hardware setup retrieving the GPS position of an object and then sends the position through a mobile communication module to a smartphone. A software application running on a smartphone simulator was developed to visualize the position with a Google map widget. The hardware unit consists of a GPS/GSM/GPRS module, a microcontroller, and a smartphone simulator that runs the software application made for iOS, Android and Linux operating systems using Flutter - an UI multi-platform software development kit. Implementation of the setup started with a Telit GM862 GSM/GPRS/3G-GPS module (together with a SmartGM862 development board), an Arduino UNO microcontroller board and a logical level converter. This first setup was not successful because a problem with the serial communication between the Telit GSM-GPS module and the Arduino could not be solved.  The second setup was implemented in which an Arduino GSM/GPRS/GPS shield was used with the Arduino board. The serial communication between the shield and the Arduino was functioning properly and a GPS position could be retrieved. The GPS position is published (sent) using a lightweight messaging protocol - MQTT (messaging queuing telemetry transport) through GPRS functions to the smartphone of the destination user.  To visualize the GPS position in a Google map, an Object Tracker app was implemented on the smartphone simulator app (an iPhone in this project) that subscribes and retrieves the GPS position, and then displays it on the map with a red marker indicating the position.  The GPS tracker with the second setup and the app has been tested and proved to work properly. It has, however, much room for improvement and further development, e.g., making the app more user-friendly, and designing and making a PCB so all the components are mounted on one board. It has been noticed in an initiated test that the GPS antenna placement could affect  positioning accuracy. This, thus, needs to be considered for high accuracy.