doxygen: It is a tool for a documentation system for various programming languages such as C++, C, Java, Objective-C
grapghvizgraphviz: Rich set of graph drawing tools. It required to fulfil the need of a centralized documentation presenting all available tools in the graphviz package.
dot: Filter for drawing directed graphs. A graph that can be drawn as hierarchy. It reads attributed graph files and writes drawings. By default, the output format dot is the input file with layout coordinates appended
perl: It is a script file used by doxygen and it should be present in the system
mscgen: Message Sequence Chart Renderer. This will help to make sequence diagram for Doxygen documentation.