Comcast is ready to compete for cord cutters. The cable giant on Sunday announced Stream, an online-only service that will let Internet customers access broadcast channels and HBO on their mobile devices.

For $15 per month, Stream will launch in Boston at the end of the summer before expanding to Chicago and Seattle and then the rest of its footprint by early 2016.

In addition to live TV (ABC, CBS, FOX, NBX, PBS, ABC, The CW, Telemundo, and Univision), customers can also watch on-demand TV shows and movies via Streampix, as well as record shows and watch them via Comcast's cloud DVR service.

"It's unlike anything we've ever offered," Matt Strauss, executive vice president and general manager of Comcast video services, wrote in a blog post. "No extra device or additional equipment required…or even a TV."

In fact, Stream customers can't actually stream content to their TV, according to the New York Times, though they could watch HBO via the HBO GO app.

Users can sign up online, download the Xfinity TV app, and start watching—without the hassle of customer service or technicians' home visits.

"We want to make ordering Stream as easy as buying a song online," Strauss said. "And making tuning in to a show as simple as opening an email."

To find out when Stream will be available in your area, sign up online.

The move comes as traditional cable firms face increasing pressure from streaming services like Netflix, Hulu, Amazon, and now standalone versions of HBO and Showtime. Consumers no longer need to pay for a cable video package to watch those premium channels, and many people, particularly younger consumers, are making do with a fast Internet connection and a subscription to one or more streaming services.

Comcast rival Verizon has already teased an Internet TV service. In March, it announced it will air 200 hours of original content from AwesomenessTV each year when its Internet-only service launches later this year.