For billions of nodes, there are two options: Graphistry (and it might be less than that, 100M is OK), and Pajek, which is weird, but can handle billions of nod

For billions of nodes, there are two options: Graphistry (and it might be less than that, 100M is OK), and Pajek, which is weird, but can handle billions of nodes. Neo4j, cytoscape, etc will not work.