With the ever-increasing capacity of the Internet and demand for human lives, Internet of Things (IoT) applications is increasing like never before, primarily to facilitate smart homes and smart cities. However, consumers have become increasingly cognizant of the negative effects of energy consumption as well as the importance of footprint reduction. Despite the increased interest in energy reduction and consumption, the average consumer still feels intimidated and unsure of how to start. In this paper, we propose an energy monitoring system (Watts On) to be used per room within a house that is efficient, intuitive, and economic (cost effective). The significant contribution of this paper is the design and development details of WattsOn prototype application. WattsOn is a low-cost IoT and cloud-based system that allows end-users to monitor, store and display energy usage data in an intuitive graphical user interface. As part of this system, we have also developed companion mobile applications in both platforms (Android and iOS), which allows the users to look at the real-time energy usage for the entire house or building to best pinpoint where excess energy is being used to understand better how to reduce consumption. The widespread use of our system will provide several benefits like saving on electricity bills by monitoring the usage and conserving the precious natural resources by reducing electrical energy consumption.