GraphX does not come with a built-in graph visualization tool, so for us to tackle visualizing massive graphs, we have to consider other options. There are many general-purpose visualization libraries out there, as well as a few specialized graph visualization tools. In this chapter, we choose Gephi for essentially two reasons:

• It is a free open source tool that is available for all the major platforms
• We can utilise a simple exchange format, GEXF, to persist GraphX graphs, and can load them into the Gephi GUI to specify the visualization with it

While the first point should be universally considered a plus, not everyone is a fan of the GUIs and it's certainly more in the spirit of most developers to define visualizations programatically. Note that this is in fact also possible with Gephi, but more on this later. The reason we chose the mentioned approach is to keep the book self-contained and the coding parts about Spark only, by still using powerful visualizations provided by Gephi.