In its lawsuit against Zillow focused on alleged infringement of copyrighted photos, CoStar Group is adding new allegations today, claiming that Zillow is continuing to “publish” images it has watermarked and identified, including some that were previously removed by the portal after the lawsuit was filed.
Originally filed back in the June of 2025, CoStar has alleged that Zillow “willfully” uses and benefits from photos CoStar owns copyrights of in order to train algorithms and attract customers, mostly in the multifamily sector.
Zillow has claimed that photos are uploaded by its customers (usually property owners or managers), and accused CoStar of “weaponizing” court proceedings for “competitive pressure” and publicity.
In a statement to RISMedia, a Zillow spokesperson claimed that the updated allegations are “yet another proof point in the weaknesses of their arguments,” and reiterated the accusation that CoStar has a pattern of “wastefully leveraging litigation rather than competing on the basis of product quality and consumer experience.”
CoStar General Counsel Gene Boxer, in a statement provided to RISMedia, said that Zillow has become “increasingly brazen” in allegedly violating copyright protections.
“Zillow has the tools to stop—it is simply choosing not to, hoping that its mass-infringement scheme will return a profit. We look forward to holding Zillow to account,” he said.
According to the updated filing, the “total number of images at issue” now stands at 53,733. CoStar claims that it has continued to alert Zillow to these new alleged violations “(t)o no avail.”
“Zillow has built image recognition algorithms capable of detecting features far more subtle and varied than an identical, consistently-placed, image watermark,” the fling reads.
Zillow previously noted that it has a process for anyone to claim copyright on a photo that is hosted on one of its platforms, and that its removal of images identified earlier were a routine step in copyright litigation and not an admission that those images were in violation of any rule or law.
The lawsuit is part of long-running rivalry between the two companies, with CoStar CEO and founder Andy Florance vocally critical of Zillow’s business practices as he seeks to power Homes.com, a CoStar subsidiary, ahead of Zillow in the so-called “portal wars.”
Editor’s note: this story was updated at 3:41 p.m. eastern time with a statement from Zillow.
