FastMindMap is also an outliner app

As compared to the Mind map view, the Outline view is more compact thus suitable for large hierarchical structures.
All the node properties such as Icons, Notes, Hyperlinks, Documents, and so on, are available in the Outline view.

A mind map is viewing in Outline view:

FastMindMap also provides an outline view for viewing your project structure

Another hierarchical structure viewing as an outline:

Outliner view of FastMindMap