The chief executive of CoStar Group, which owns Apartments.com, said Zillow has ‘stolen’ thousands of images to bolster its business.

The case, filed in a New York federal court on July 30, includes claims Zillow is using watermarked images owned by CoStar Group — parent company of competing home search site Homes.com — on its sites and on Redfin and Realtor.com through its rental listings syndication deals.

CoStar claims Zillow published more than 46,000 of CoStar's copyrighted photographs on Zillow.com and partner sites.