IoT-based cardiac monitoring systems face challenges related to both accuracy and convenience. The integration of real-time wearables based on AD8232 and ESP8266 has not been widely explored in practical applications. This research aims to develop an affordable, portable, and reliable heart monitoring solution. Specifically, it focuses on designing and testing the Heart Vest as a real-time heart monitoring system based on IoT and mobile applications. Experimental research was conducted by testing IoT devices using AD8232 and ESP8266 sensors. Data were transmitted to Firebase and visualized through an Android application. Tests on sensor accuracy, data synchronization, and BPM status classification were carried out to verify system reliability. The test results show that the AD8232 sensor achieved an average accuracy of 97.8% (2.20% error rate). Data synchronization between the Heart Vest LCD and the mobile application reached 100%. The system successfully classified heart status (normal, alert, danger) with 100% accuracy and provided real-time alerts via LED and buzzer. These findings demonstrate the reliability of the Heart Vest as an efficient, economical, and responsive real-time monitoring system for non-clinical use. Moreover, the results reinforce the potential of IoT-based wearable systems in cardiac monitoring applications. Future research should include clinical trials and multi-sensor integration to further enhance functionality and clinical accuracy.