See also WorldCat:

> WorldCat is a union catalog that itemizes the collections of 17,900 libraries in 123 countries and territories[4] that participate in the OCLC global cooperative. It is operated by OCLC, Inc.[5] The subscribing member libraries collectively maintain WorldCat's database, the world's largest bibliographic database.[6]

* https://en.wikipedia.org/wiki/WorldCat

* https://www.worldcat.org

that would be great, if it had an open API

It is useless without API

Open Library looks like it has a decent API: https://openlibrary.org/developers/api

Also, user review, lists and tagging/bookshelves. Just massive data

Hopefully the Justice department can use this as fodder for a potential breakup. It clearly demonstrates how monopolies kill competition, not by competing but by buying and extinguishing.