Energy monitoring system becomes an important subject to provide information of electricity usage for the users. Due to advances in electronics and computing, many technologic solutions are now available. These solutions are very important tool to a sustainable future. Hence, this paper presents the digitization of a low-cost small-scale energy monitoring systems based on IoT. The proposed energy monitoring system known as EMOSY is designed to eliminates the high-cost energy meter. EMOSY is a portable and practical system which can be used without modification of internal or external connection of appliances. EMOSY is developed by using a voltage detector circuit concept by amplifying the existence of electrostatic. This electrostatic reading sends to the database through Wi-Fi module ESP8266 integrated with Arduino NodeMCU. The web page is designed using Adobe Dreamweaver with HTML and PHP coding. In the proposed system, the user able to monitor the energy usage of each appliance and estimated billing time to time. Based on the result, the energy monitoring system successfully can detect the existence of electrostatic, and the webpage database can display the energy usage extended to the estimated electricity bill. The monitoring system is found to be useful to the residential, commercial, and industrial to monitor energy patterns, which is essential to facilitate energy conservation measures for
minimizing energy usage.