NGPy is a web application that enable online performing and analyzing computer simulations. NGPy aims to provide a unified platform for managing settings, logging, distributing simulation tasks, real-time monitoring, data storage, and graphical data analysis. Currently Monte-Carlo simulations of nucleation and growth phenomena are supported. However, It can be simply extended to develop simulation-specific web applications. NGPy is built on top of Flask and employes numpy for simulation tasks and matplotlib for visualization. NGPy is actually a distributed system since we use ZEO server as a database and redis server as a message queue.