qwViz: Visualisation of quantum walks on graphs. qwViz is a software package for interactive visualisation of the time-evolution of quantum walks on arbitrarily complex graphs. The package is written in C and uses OpenGL to generate graphics in real-time. The qwViz package can be used to directly simulate discrete-time quantum walks on undirected graphs when provided with the adjacency matrix of the graph. For more detailed studies, qwViz can also be used to visualise externally generated quantum walk data written in an XML-based file format (QWML). Various aspects of the visualisation can be customised and manipulated in real-time, allowing quantum walk dynamics to be probed at various length and time scales