America’s four major broadcast networks joined forces on Wednesday to sue a little-known nonprofit organization that streams television signals at no charge, arguing that the service should be shut down for copyright violations and for failing to compensate them.

The service, Locast, started last year and is available through a free app that relays broadcast feeds online. It has more than 200,000 users in 13 cities, including Chicago, Los Angeles, New York, San Francisco and Washington.

The networks, ABC, CBS, NBC and Fox, say in their complaint that Locast is eating into the licensing fees they get from pay-television companies like the cable operator Comcast and the satellite-TV provider Dish that carry the networks’ programs and sports events. The networks are expected to receive more than $10 billion in such fees this year.

“A rogue streaming service skirting the law for the benefit of telecom giants does nothing but threaten the very investments in content that consumers value,” the networks say in the complaint, which was filed in the Federal District Court in Manhattan.