Food delivery apps such as GrubHub and Uber Eats are using “unlawful” contracts to bolster their grip on the market for meal deliveries and drive up prices for consumers, according to a new civil antitrust suit in Manhattan federal court.

The proposed class action lawsuit, filed late Monday in the U.S. District Court for the Southern District of New York, targets GrubHub Inc., DoorDash Inc., Postmates Inc. and Uber Eats over their use of “no price competition clauses,” which force restaurants to charge uniform prices for menu items, even for food orders that were not generated through their digital platforms.