Yes, Google Books is still an active service, and it provides developer APIs
to interact with its repository.
Google offers two main components for developers:
1. Google Books API
This is a REST API that lets you programmatically access book data. Common use
cases include:
 * Search: Performing full-text searches across the Google Books repository.
 * Book Details: Retrieving metadata, pricing, availability, and links to
preview pages for specific volumes.
 * Bookshelf Management: Allowing users to view, manage, and categorize their
personal "My Library" bookshelves.
2. Embedded Viewer API
This JavaScript API allows you to embed Google Books previews directly into
your own website. It provides programmatic control over the embedded viewer,
allowing you to build controls to turn pages, zoom in or out, or highlight
search terms within the book.
Authentication & Limits
 * Public Data: Searching for books or retrieving basic volume information
only requires a standard Google API Key.
 * Private Data: If your application needs to access or modify a user's
personal bookshelves, it requires OAuth 2.0 authentication to get user
consent.
 * The API is free to use but is subject to a daily quota limit. You can
request quota increases through the Google Cloud Console if your application
needs to make a high volume of requests.