We present Toa, an open source web based NetFlow data network monitoring system (NMS). Toa consists of a collection of scripts that automatically parse NetFlow data, store this information in a database system, and generate interactive line charts for network visualization analytics. The system is pseudo real time, meaning that it continuously updates the interactive charts from NetFlow data that is generated every five minutes. The system allows the users to generate customized charts from the data stored in the database system.