The GridPort Toolkit (GridPort) enables the rapid development of highly functional grid portals that simplify the use of underlying grid services for the end-user. It comprises a set of portlet interfaces and services in the portal layer that provide access to a wide range of backend grid and information services provided by lower-level grid technologies including the Globus Toolkit, the Grid Portal Information Repository (GPIR), and Condor. Portlets expose the backend services via customizable web interfaces in order to enable personalization of grid portal user interfaces. Portal services support the portlets inside the portal layer by augmenting their capabilities in an extensible and reusable way while tying the portlets together in order to make them more cohesive. GridPort is intended for use by developers of grid-enabled portals, portlets, and applications.