In the conventional tempe-making process, the soybean fermentation process is carried out by spreading the wrapped soybeans in the open, in this case the temperature and humidity that affect the growth of molds are not measurable. Therefore, it is necessary to design a device to control temperature and humidity in the soybean fermentation process with the integration of mass sensors and internet modules in it. The mass sensor and IoT are intended so that the tool can warn users that soybeans are indicated to be fermented and can be controlled remotely through the Blynk application on a smartphone. The temperature and humidity control system is designed to work using an on-off control mode with a temperature range between 30℃ - 35℃. The temperature sensor used is a DHT22 module which can also measure humidity. For mass sensors, a load cell module is used to measure changes in soybean mass as an indicator that soybeans have been fermented. The controller used is the Arduino Uno module as the main controller and the ESP32 module as the IoT controller. The actuator consists of two incandescent lamps placed above and below the soybean. From the soybean fermentation test that has been carried out, the soybean fermentation time using a tool is faster than the conventional fermentation time. Fermentation on 250 grams of soybeans using a tool is 11.4 hours faster than conventional fermentation, on 500 grams of soybeans it is 7.7 hours faster, and on 750 grams of soybeans it is 2.1 hours faster. For changes in soybean mass, the three variations showed a reduction in the mass of fermented soybeans. The mass of fermented soybeans is reduced by about 3% – 7.6% from the initial mass.