Fires are a global problem that has many causes and devastating consequences, especially since they can cause death, environmental pollution, and destruction of property. The most common type of accidents are those caused by fire. They can occur due to many things, such as gas leaks, damage to wiring, negligence in managing flammable materials (such as fuel, cigarettes, matches, etc.), and careless use of tools and combustion that are usually used to cover up criminal activities. This study will create an Internet of Things-based automatic fire extinguisher by using somke detector to detect the presence of fire smoke, ESP8266 as an electronic device that processes the input and output of the device, buzzer as an output that converts electrical vibrations into vibrations, and 5V water pump as an output to pump water and Short Message Service (SMS) to send notifications when there is a fire warning. Tests on the smoke detector showed that only 10% of trials failed to detect smoke from the fire and turn on the fire extinguisher pump, and 90% of the tools functioned properly to detect smoke. This failure is possible because the smoke is so thin that it has not reached the detection threshold of the sensor used. In general, the device can operate well
