https://github.com/EbookFoundation/river-of-ebooks

The River of Ebooks serves as an easy-to-use ebook aggregator. Publishers can send metadata from new and updated ebooks through the River where it will be available for any downstream consumers to read, allowing for a more widely available ebook collection. This way, ebooks can be made available on all end user sites, instead of only the site they were published with.

The River provides a filterable feed of ebook metadata in OPDS2 format. Consumers can use this to find new ebooks to catalogue, and can then choose to receive updates to the metadata when new revisions of the ebook are published.

Consumers can find books without searching through the feed as well - just enter some filters and get notifications sent to a webhook whenever a book matching your filters is published.

Whenever a publisher sends ebook metadata through the River, it will be sent to any consumers who have chosen to be notified about changes to the book. This saves the publisher and consumers the trouble of having to worry about everyone having the latest version of the content.