Localization is a key IoT application that facilitates elderly-people monitoring, animal tracking, asset management, etc. However, most IoT devices are power-constrained, inhibiting the use of traditional GPS/GNSS modules owing to their high-power consumption. Further, the coverage of GNSS is drastically affected in indoor environments. Thus, we propose a GNSS-free localization of IoT devices using LoRaWAN, a low-power and long-range communication technology. The estimated battery life of LoRaWAN devices is in the order of years as compared to hours/days of GNSS trackers. A key requirement of time-based localization is the synchronization of gateways/anchor nodes. This is typically achieved using accurate time provided by GNSS. Alternatively, we solve the synchronization requirement using a stationary node to simultaneously reset the clocks of all gateways.