Google's PageRank patent has expired (2019)
I'm not sure how useful this might be to anyone anymore.<p>Google still uses it for the base ranking.  But, the results are then run through a variety of add-on ML pipelines, like Vince (authority/brand power), Panda (inbound link quality), Penguin (content quality), and many others that target other attributes (page layout, ad placement, etc).  Then there's also more granular weightings for things like <i>"power within a niche"</i>, where a new page might do well for plumbing (because of other existing pages on the site), but wouldn't automatically have any authority for medical topics.