Grappa: A graph package in java. Grappa is an extensible graph drawing package written in Java. The package comprises classes that implement graph representation, presentation and layout services. It provides an application programming interface (API) on top of which Web-based applications that need to visualize information in terms of graphs, such as process flows, business workflows or program dependencies, can be built. Through subclassing, the classes that implement an application inherit graph drawing and layout services provided by Grappa, these services can be enhanced and customized for the specific application. To illustrate its utility, a new version of Improvise, a multimedia process modeling environment, was written on top of Grappa.