Correction: An earlier version of this article incorrectly described Metro as the second-largest transit system in the country. The system, including rail and bus service, is the fourth-largest in the country by ridership, according to the American Public Transportation Association. Metrorail is the second-largest subway system in the country by ridership, according to the association. This version has been updated.

Developers of transit apps for smartphones say Metro unnecessarily limits the data it provides, and when the transit agency does provide information, it is often sloppy and inaccurate.

Their concerns came to light after the popular app NextBus DC suddenly stopped working late last month because of a contract dispute involving the creator of the technology behind the app and the company that now controls that technology.

The developers of NextBus DC said they are reworking their app and plan to relaunch in the coming weeks.

The outage led about 7,000 D.C. area commuters to e-mail the app maker with complaints, a sign of how many riders have come to rely on technology to make their trips more efficient and predictable.

The frustration comes as Metro — the second-largest subway system in the country by ridership after New York City’s — has experienced declining ridership as it tries to rebuild its aging system, conducting major track work nearly every weekend.

But app developers said the troubles with Metro’s data go beyond the contract dispute between Ken Schmier, who founded the company that created the tracking technology used in the NextBus apps, and Emeryville, Calif., company NextBus Inc.

One problem, developers said, is that some of the information Metro provides developers for its bus system was missing data on route destinations. At other times, developers said, “weird” formatting or perhaps a software bug makes the name of a bus route — such as the 10A — appear as the time, as in 10 a.m.

When developers raised their complaints to Metro in online forums, they’ve gotten little or no response, they said. They point to mistakes in the data that were brought up years ago and have yet to be fixed.

Andy Monat, an app developer in Boston who recently made a smartphone app called, said he found two-thirds of Metro’s 600 bus routes had a variety of troubles. Some bus routes showed up with error messages or read “testing” in the route name, Monat said. Others were missing data entirely. Many had no stops listed at all for the route or only a handful when they should have showed a dozen or more.

In an interview Tuesday, Metro spokesman Dan Stessel defended the agency’s efforts to encourage app development. He said Metro does not make the NextBus data directly available to app developers, because “we’re trying not to get locked into one vendor because then you’re locked into just that one.” He said there aren’t problems with its data and that developers who said there are problems are “mistaken.”

Ian Dixon, who developed an app called DC Metro and Bus, said the information Metro provides for app developers is “amateurish.”

“It is really bad quality of data,” said Dixon, whose app has been highly rated by iPhone and Android users.

“It’s an impediment to building something.”

But Dixon said he recently ran into another problem with the train data Metro provides.

Because his app is so popular, he said, he went beyond the limits Metro sets for the amount of data that can be pulled at any given time from its servers. That caused Dixon’s app to have sporadic outages around the Christmas holidays, leaving riders at rush hour in the dark.

“If you’re going to have an app that’s a success, you’ll blow through their data limits,” said Dixon, who has free and paid versions of his app.

However, Stessel said that in the past month, the agency has “nearly quadrupled” the amount of data a developer can utilize.

But developers have other concerns. When Dixon reached out for help in a Metro-sponsored online forum and sent e-mails over the past few weeks to Metro officials who maintain the data, Dixon said he only got a “very casual response.”

“I’m dependent on these guys who support these things,” he said. “One day of an outage on an app can affect the success.” Making apps and keeping them maintained is competitive, Dixon said. If an app doesn’t work consistently, “it is going to kill you.”

Stessel said Metro is working to create a “better line of communication” with app developers. He said the relationship Metro had with apps developers “lacked ownership” inside the transit agency for who would respond to questions, but promised there would be changes, although he wouldn’t name the person who would be in charge of app developers.

“In the near future, developers will notice an improvement in our outreach to them and the responsiveness to any issues they may have,” he said.

App developers have other concerns about how Metro provides data on its buses.

Monat said Metro is “backwards” in how it puts out information for developers to use in building apps. Even though many large transit agencies, including Boston and Los Angeles, allow NextBus Inc. to provide a direct feed of its customized bus arrival data to third-party developers, Metro does not. Instead, Metro puts the information on its Web site, where developers retrieve it.

It means that existing apps that work in other cities and are based on the NextBus technology don’t work for Metro, according to developers and NextBus.

Stessel said riders can find the information NextBus provides the transit agency on Metro’s Web site. But some riders have complained that the data isn’t always reliable.