This paper focuses on the design and application of low power and low-frequency localization system using received signal strength indication (RSSI). The receiver will wake up from sleeping mode by a modulated magnetic field emitted from a transmitter module. Then it will send messages containing the Received Signal Strength Indication (RSSI) via WiFi with Message Quest Telemetry Transport (MQTT) protocol to an MQTT broker. Using the magnetic coupling effect and RSSI ranging, the system is a unique candidate for low power security-positioning purposes.