Read more: Realtors settle with DOJ over broker commissions

“We launched REX to put the consumer back in charge of real estate and transactions,” said REX chief executive Jack Ryan. “This case builds on the DOJ’s recent antitrust settlement with NAR/MLS that beat back some anti-competitive practices. We believe this litigation will define whether technology will serve and protect big brokers and the NAR cartel or whether it will make good on its promise of greater ease, service, transparency and lower commission fees for consumers.”

Now, NAR is suing the company back for falsely, it claims, advertising that home sellers can bypass commission fees, when, in reality, REX’s seller-clients may still have to pay commissions when a homebuyer is represented by an agent.

NAR also noted that REX claimed that its “innovative and superior technology” – which uses artificial intelligence and data analytics to identify the “perfect” buyer for a seller’s property – offers lower commission fees. However, REX admitted it relies on Zillow’s website to display its listings.

“Independent, local multiple listing services benefit competition and fair housing, and NAR will ensure consumers can make the choice to participate in local broker marketplaces, or not, with a full understanding of how they work,” said NAR president Leslie Rouda Smith.