This missed the biggest technical moat by a mile: data.
Book data is scarce and expensive. Goodreads gets it for free because of Amazon, Amazon gets it subsidized because of Amazon's chokehold on book publishing. Any Goodreads competitor needs to license paid data and sort through the duds and the duplicates, and struggle to match up book with only ASINs that are on Amazon Kindles and nowhere else.
And Kindle integration. When you finish a book on a Kindle, it asks you to review it on Goodreads. If you want to add an option to review it on $otherstartup website, your best bet is a supreme court antitrust case.
Book data is scarce and expensive. Goodreads gets it for free because of Amazon, Amazon gets it subsidized because of Amazon's chokehold on book publishing. Any Goodreads competitor needs to license paid data and sort through the duds and the duplicates, and struggle to match up book with only ASINs that are on Amazon Kindles and nowhere else.
And Kindle integration. When you finish a book on a Kindle, it asks you to review it on Goodreads. If you want to add an option to review it on $otherstartup website, your best bet is a supreme court antitrust case.