In a move that could hasten the slow pace of so-called TV Everywhere, a technology start-up is introducing a way to move a whole subscription’s worth of TV onto the Web, with or without the subscription company’s permission.


The start-up, called NimbleTV, will begin testing its service with a limited number of users on Monday. The service takes the package of television channels that a customer buys through a distributor like Dish Network, then streams the package onto the Web, allowing the customer more options for viewing than most distributors now allow. It also allows for thousands of hours of TV recording via a virtual digital video recorder.


NimbleTV is the latest example of technology companies trying to break into the closed system of television distribution in the United States. As Americans buy more smartphones and tablet computers, cable and satellite distributors are under pressure to provide TV access on more screens, and entrepreneurs are — depending on one’s view — either helping to provide it, or forcing it to happen on their own terms.


Large companies like Apple and Google have taken steps to enter the television distribution business.. So have start-ups like NimbleTV, which is backed by the venture capital firms Greycroft Partners and Tribeca Venture Partners and by the Tribune Company, the owner of 23 TV stations.


“We’ve all heard about TV Everywhere for a long time. One of the questions that’s bothered me is, why is it not here yet?” said Anand Subramanian, the chief executive of NimbleTV, during a preview of the service at Greycroft’s Midtown Manhattan office last week.


TV Everywhere is a slogan for a nearly three-year-old effort by TV distributors and channel owners to make channels available to subscribers on all screens at all times. Despite some notable successes, the effort has been stymied by outdated contracts and by concerns that new ways of TV viewing will generate less revenue than the old ways.


As a result, many technologically adept television viewers have voiced some variation of the same complaint: why can I not watch any show on any device at any time? That availability is what NimbleTV is pushing.


“It picks up where Slingbox left off,” said Jason Hirschhorn, a former executive at the maker of the Slingbox, Sling Media, who is now an adviser to Greycroft and a supporter of NimbleTV.


When the Slingbox device is hooked up to a TV set, users can log in on a computer from anywhere and view whatever is live on their DVR at home — a useful feature for watching a home team’s baseball games while on the road, for instance.


Sling Media is owned by EchoStar, which is controlled by Charles W. Ergen, the satellite media mogul who also controls the Dish Network. Dish promotes the Slingbox to its subscribers as its form of TV Everywhere. But the device has not been embraced by other distributors.


NimbleTV says it has the same functionality as a Slingbox and DVR, but without the actual boxes. Mr. Subramanian, a Giants fan, recounted watching the Super Bowl through the service while on a work trip in India.


Within the cable world, the closest thing to NimbleTV is an app from Cablevision that replicates its subscribers’ live television lineups on tablets, phones and computers. The app works only within the subscriber’s home, however. Time Warner Cable has a similar app that replicates part of the lineup.


NimbleTV also raises the tantalizing prospect that users could shop around for television subscriptions — removing the physical constraints that now give companies like Comcast and Cox exclusive cable licenses in cities.


But that will not happen for a while, if at all. The company’s test phase, which begins Monday, is limited to New York City and to a set of 26 channels that the company will pay for. It plans to start letting people sign up for satellite service through its software this summer.


The service is positioned by Mr. Subramanian and his supporters as a way to enhance existing cable or satellite packages and to help distributors sell more such packages. “Our intention is to support as many providers as possible,” he said. But he declined to name any providers that are already on board, and he asserted that NimbleTV did not need their blessing.