Free, Open-Source 3D Maps

OpenGlobus is a javascript library for creating interactive 3d globes. The library uses WebGL and is completely open-source and free to use.

OpenGlobus supports GeoJSON, map tile layers, image and video overlays and vector layers for displaying polylines and polygons. The API for OpenGlobus is well documented, however as yet there aren't any written tutorials for getting started with the library. If you want to make an OpenGlobus map then you are probably best starting with one of the many demo maps. You can get a good idea of the range of features that OpenGlobus supports on the Examples page, which includes a number of demo 3d globes created with OpenGlobus.

You might also like CesiumJS, which is another an open-source JavaScript library for creating interactive 3d globes and maps.