System

Erm, hmm.

System is a free, open, and living public resource that aims to explain how anything in the world is related to everything else.

https://www.system.com/graph

Overview: https://about.system.com/about/overview

Annoucing the public beta: https://about.system.com/blog/announcing-the-public-beta-of-system

(h/t Systems Change Finland)