Nowadays, Internet of Things (IoT) hardware and technologies are getting more and more importance in our everyday lives: these small, low-cost devices, composed of sensors and transmission capabilities, are more and more popular. Despite all of this, these systems present some drawbacks and developers are forced to find compromises between measurement accuracy, battery duration and system costs, trying to optimize all these variables for deploying amazing smart applications. Sensor fusion is one of the emerging techniques for analysing heterogeneous data coming from different sensors, to get accurate information to be exploited in several IoT applications. However, for the correct implementation of sensor fusion models, synchronization of the heterogeneous signals is a must.