The UDIG GISPlatform is built around the concept of plug-ins to the base Eclipse Rich Client Platform. Several other well-known eclipse plug-ins are used, such as the Eclipse Modeling Framework and the Graphic Modeling Framework.

It is useful to consider the UDIG application as a series of Tiers each with different responsibilities and capabilities.

• Tier 0: The Toolkits used, such as Geotools and GeoAPI, provide useful abstractions (such as Features) and data connectivity. These libraries are all gathered into the net.refractions.udig.libs plugin so they may share a classloader.
• Tier 1: Catalog Services provide a common API for data access and may serve as foundation for different GIS applications
• Tier 2: Project services opperates as a UDIG application providing Maps and Printing under user control
• Tier 3: Rendering and Tool services allow control of display and screen interaction.