CoStar amends lawsuit against Zillow, alleging further copyright violations

Arlington County-based CoStar Group last week filed an amended complaint against Zillow Group, alleging that the company continued to infringe on its copyrighted images even after CoStar filed a lawsuit against it last summer.

In July 2025, CoStar and its subsidiary CoStar Realty Information sued Zillow in the U.S. District Court for the Southern District of New York, alleging the company used nearly 47,000 CoStar-copyrighted images illegally. The lawsuit claimed Zillow published the images on Zillow.com and other Zillow sites, as well as distributing CoStar’s copyrighted photos to partner sites, including Realtor.com and Redfin. CoStar also alleged direct and vicarious copyright infringement and sought injunctive relief and damages.

But in its March 27 amended complaint, CoStar alleges the infringement continued. The filing identifies thousands of additional images, many bearing CoStar’s watermark, that were allegedly used after the initial lawsuit, bringing the total to more than 53,000 images displayed over 250,000 times.

“Since CoStar Group filed this lawsuit in July 2025, Zillow’s infringement has only gotten worse — and increasingly brazen,” CoStar General Counsel Gene Boxer said in a statement.

Boxer alleged that Zillow infringed thousands of newly copyrighted CoStar images after being sued. The amended complaint features screenshots of photos on Zillow’s website that it alleges are CoStar’s.

“Even worse, after claiming to have removed the images CoStar specifically identified in its original complaint, Zillow turned around and re-published many of those very same photographs,” Boxer said. “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.”

CoStar’s amended complaint said that an internal Zillow strategy document from December 2024 acknowledged that Zillow was at risk of being sued specifically by CoStar for improperly using CoStar’s photographs. CoStar did not provide a copy of the document.

The complaint states that Zillow claimed the copyrighted images were uploaded by its customers but offered no evidence, and accused Zillow of trying to “blame its customers.” It noted that the discovery will address the various sources from which Zillow obtained the photographs.

“But in any event, even if users were responsible for uploading some of CoStar’s images to Zillow’s websites, Zillow is independently liable for its own decisions to retain, store, display, rearrange, syndicate and commercially exploit all of CoStar’s images at issue,” the complaint said.

For example, the complaint alleges Zillow builds “unclaimed” property pages using CoStar images to populate rental listings on its platform and partner sites. CoStar also alleges that Zillow uses its images in online Google ads and feeds them into its systems to train its algorithms and develop key platform features.

CoStar alleged that Zillow has failed to use its image-analyzing software to detect and remove CoStar watermarked photographs from its platform. CoStar said the violations occurred despite sending Zillow four letters from August 2025 to February notifying Zillow of its ongoing infringement.

CoStar is still seeking injunctive relief, “substantial” damages and the permanent removal of all CoStar images from Zillow’s systems.

In February, Zillow filed a motion to dismiss CoStar’s claims, arguing its competitor had failed to “state a viable claim” and that CoStar’s lawsuit was “part of a broader pattern… It remains clear to Zillow this is a media stunt and effort to stifle competition and innovation.”

In a Tuesday statement, Zillow did not directly respond to detailed questions about the new allegations. Instead, a Zillow spokesperson provided a statement.

“CoStar’s decision to amend the complaint rather than respond to our motion to dismiss is yet another proof point in the weaknesses of their arguments and also a perpetual model of wastefully leveraging litigation rather than competing on the basis of product quality and consumer experience,” the spokesperson said.

Zillow has faced numerous legal challenges within the past year.

In June 2025, real estate brokerage company Compass sued Zillow in the U.S. District Court for the Southern District of New York, challenging Zillow over its policy of excluding many private home listings. According to the Associated Press, Compass claims Zillow “has sought to rely on anticompetitive tactics to protect its monopoly and revenues in violation of the antitrust laws.”

And in October 2025, then-Virginia Attorney General Jason Miyares and attorneys general from several other states filed an antitrust lawsuit against Zillow and Redfin in the U.S. District Court in the Eastern District of Virginia, arguing that the two companies entered into an unlawful $100 million agreement not to compete with one another. In December, the case was merged with the Federal Trade Commission’s antitrust lawsuit against Zillow and Redfin.