I'll talk about the current state of mago3D project, an open source based Digital Twin platform. mago3D(https://github.com/Gaia3D/mago3djs) is a relatively new project first released in July 2017. The ultimate goal of mago3D project is developing an open source based digital twin platform that can replicate and simulate the real world objects, processes, and phenomena on web environment. mago3D is on its way to achieve this goal now. As a Digital Twin platform, it can integrate, manage, and visualize various kinds of data formats sucs as CityGML, IndoorGML, LAS, IFC, 3DS, and other popular GIS formats. It utilizes tons of open source projects as a baseline framework. mago3D has been used in various industry sectors including ship building, urban management, indoor data management, and national defense. In this talk I'll showcase several real projects that employed the mago3D and will talk about recent improvements and new features of mago3D.