Wal-Mart, the largest US retailer, has launched a free classified ads service on its Walmart.com website in an alliance with Oodle.com, a small California start-up that is seeking to challenge the dominance of Craigslist.

The listings on Walmart.com draw on its own users and hundreds of thousands of listings from Oodle’s other partners, including The Washington Post and Cox Media, and currently include a horse for sale for $400 in Stewart, Tennessee, a $5,500 Honda motorcycle in Burleson, Texas as well as houses and jobs.