ViViaN(TM) (Visualizing VistA and Namespace) was an OSEHRA developed, web based tool for viewing and browsing relationships among hierarchical and connected entities. Today.WorldVistA maintains it.

Originally developed to allow browsing of the VistA code base via a tree-based functional decomposition of the code, ViViaN has expanded to include tree-based visualizations of VistA menus and the VHA Business Function Framework categorization; as well as circle plots of the interaction network among VistA packages.