Microsoft C#UNG (pronounced “chung” and short for C# Universal Network/Graph System) is a desktop application that displays graphs, which are collections of vertices connected by edges. C#UNG can read graphs in several file formats, lay them out using one of several layout algorithms, and display them with a variety of display options. An Excel add-in enables graph data entered in an Excel worksheet to be displayed easily in C#UNG. The components used to develop the application are available as an API for developers who want to create and display graphs in their own applications.