Home security includes services like gas leakage and trace pass protection. This system is very beneficial for old ages and handicapped people as well for working people, it is a blessing as it alert the person if any nasty situation raised at home in their absence. Though there are various technologies used but in every technology mobile plays important role, to automate home appliances or to get alert in risky situations. Attractive GUI can be used for smart home system, accessible with smart phones, tablet, laptop and PC. A comparative study of smart home system based on technologies like GSM, Bluetooth, IOT and PIC Microcontroller with ZigBee modulation is discussed here.