With the development of 3D applications related to geography, the standards and specifications for the provision of corresponding data are increasingly coming into focus. The presentation deals with the current development status of the CesiumJS library as well as the standards and possible uses of individual features and shows some examples from a recent project, in which we presented underground 3D geodata. Thus, this contribution can be seen as a renewal of our 2013 FOSS4G contribution entitled "Modelling 3D Underground Data In A Web-based 3D-Client". Not only are web-based open source 3D applications with a geographic reference constantly developing, but the development of standards and specifications for the presentation of 3D data on the web has also increasingly come into focus. A large number of libraries can be used for the representation on the web (e.g. x3dom, o3d, threejs, BabylonJS, Open GEE). Another library that has been growing steadily for several years is CesiumJS. This is used to process geographical questions in numerous areas. These include the real estate market, urban planning, sports or the various environmental sciences. In our talk we will present the current development status of the library and some possible use-cases of the features and data of CesiumJS will be briefly presented using projects as examples. A focus will also be placed on the requirements of the browser. In addition to the general availability and provision of data, the possible uses of individual selected features of the library will also be presented and discussed. When the world is represented digitally, corresponding data should also be placed there. Depending on the area of application, this can involve a relatively large amount of data, which is the case when dealing with underground data. Ideally this data should also be placed on the map in a simple way. There are already standards for the webbased-presentation of 2D-data in the web, new standards have been developed for the presentation of terrain, 3D models, buildings and point clouds as part of the development of CesiumJS. With 3D Tiles, an OGC community standard is now also available. Authors and Affiliations – Holthausen, Michael Adams, Till terrestris GmbH & Co KG Track – Software Topic – Data visualization: spatial analysis, manipulation and visualization Level – 1 - Principiants. No required specific knowledge is needed. Language of the Presentation – English