<![CDATA[This research is motivated by the lack of availability of electrocardiography (ECG) in healthcare facilities. The aim is to design, build, and test an IoT-based, portable and low-cost heart rate or ECG signal monitoring system that displays data in real-time. The system is designed using Blender and Fritzing for circuit schematics. The construction of both hardware and software development, including creating system blocks, casing, and display on IoT On/Off and PlotJuggler. The results of the ECG signal can be displayed on the device's monitor screen or sent via a server over long distances. Medical experts can use this tool remotely to monitor the condition of heart patients. This system consists of several parts, namely a data acquisition unit consisting of an AD8232 ECG sensor and ADS 1115 ADC converter, a data processing unit in the form of an ESP32 microcontroller, a data transfer unit in the form of Message Queuing Telemetry Transport (MQTT), a computer, a real-time ECG plotter GUI, and a power supply unit. The system output displayed a stable signal on the serial monitor and the computer with a GUI ECG real-time plotter. The accuracy of specific PQRST wave patterns was calculated for both rest and stress conditions, yielding a percentage accuracy of 93.93%. The precision of the ECG system was calculated by repeating data collection five times and obtaining average of rest and stress conditions equal to 95.45%. This design system works effectively in the integration of a portable low-cost ECG acquisition system with MQTT-based real-time ECG visualization for remote monitoring applications. The developed system has potential applications in telemedicine and remote healthcare services, particularly in low-resource and geographically isolated areas where access to conventional ECG equipment is limited.]]>
