Cesium is a WebGL virtual globe and map engine.
Our mission is to create the leading web-based globe and map for visualizing dynamic data. We strive for the best possible performance, precision, visual quality, ease of use, platform support, and content.
Apache 2.0. Cesium is free for both commercial and non-commercial use.
Check out the wiki, including the features, quick start, and architecture pages. Also browse the forum.