You can do an impressive amount of diagramming with the free yED. It also has some automatic layout tools and so on. It's also cross-platform so everybody can u

You can do an impressive amount of diagramming with the free yED. It also has some automatic layout tools and so on. It's also cross-platform so everybody can use it. The gallery has some impressive examples in it. https://www.yworks.com/products/yed https://www.yworks.com/products/yed