As the Internet of Things (IoT) continues to evolve, IoT device sensors today have reduced in size and cost and are now easily available. Modern IoT device sensors are also able to give accurate remote real-time data measurement. Some of IoT technologies are optimized for low power use, making them ideal for IoT and sensor applications with requirements on low system energy usage. Example is a wireless sensor node that is required to do its job for an extended period (in some cases, years) while powered by a battery. Connecting the device to a IoT cloud network can create a system for collecting and storing data measurements. The collected data could then be used for more complex application scenarios like data visualization, alerting and machine learning tasks. This paper demonstrates an open source based real-time indoor environment monitoring system for collecting, storing and visualization of data with a simple alert notification system. The results show that proposed low-cost, low-power, open-source based systems can provide high reliability while ensuring low energy consumption.