Indiana Philosophy "Ontology" Project

Here's the link. It takes you to the front door.
I've put "ontology" in scare quotes because the term is used as it is in computer science, which is not quite its meaning in philosophy proper. The Indiana Philosophy Ontology Project is about philosophy, and its conceptual structure, and not about the world at all.
As it says on the front door:

Philosophy Big Data
The InPhO analyzes over 37 million words of philosophical content from:

• Stanford Encyclopedia of Philosophy

• Internet Encyclopedia of Philosophy

• PhilPapers

• HathiTrust/Google Books Collection

We are committed to open access, with data available via a REST API, a monthly OWL archive of the ontology, visualizations and datafiles postedon our datablog, and source code at GitHub. All data uses the Creative Commons BY-NC-SA 3.0 license.

This is digital humanities. Have fun poking around.