The authors have created two toolkits that allow developers to easily integrate graph visualization capabilities into custom software applications. The Graph Layout Toolkit (GLT) provides interfaces for modeling, drawing, and automatically laying out graphs. The Graph Editing Toolkit (GET) provides a customizable display and editing layer, which facilitates rapidly developing tools that visualize data in the form of graphs. The authors present an architectural overview of these tools and discuss the challenges encountered during implementation and integration of theory and research results into such tools, In particular, they discuss automatic graph layout and labeling algorithms and complexity management techniques. In addition, they present examples of applications using these tools.