BEIJING — One of the most popular new apps in China poses an awkward question: “Are you dead?”

An app by that name has gone viral as a digital “check-in” aimed mainly at the growing number of young people living alone in China’s sprawling cities. The idea is to designate an emergency contact person, who will be alerted if a user goes a few days without confirming their well-being on the app.

The app, which was free when it launched last May but now costs 8 yuan ($1.14), was the most downloaded paid app in Apple’s App Store for China in recent days – though after its viral popularity, it appears to have since disappeared from the Chinese App Store under unclear circumstances.

The app describes itself as a personal safety assistant, “whether you are a professional living solo, a student studying far from home, or anyone choosing an independent lifestyle.”

Ian Guo, one of the founders, told NBC News he was surprised by the success of the app, which cost less than $150 to make and is now valued at around $15 million.

He said he and his two co-founders, who like him are members of China’s “post-95 generation,” were inspired by social media commenters who said this was something they needed.

“We saw this opportunity and asked ourselves if we could quickly launch a product,” Guo said. But they also believed the app “could truly provide people with more security and protection.”

“I personally lived alone in Shenzhen for a long time, so I understand the various problems one faces when living solo,” he said, adding that the sense of loneliness and insecurity “is constant.”

Though the concept may sound morbid, the app’s popularity is a reflection of demographic changes in China, where urbanization, falling marriage rates and long work hours have left many feeling isolated.

By 2030, China — a nation of 1.4 billion people — could have 200 million one-person households, according to the state-backed Global Times newspaper, which cited real estate research institutions.

The app’s name in Mandarin, “Si Le Ma,” appeared to be a play on the name of one of China’s most popular food delivery apps, “E Le Ma,” which means “Are You Hungry?” Some found its emphasis on death too dark, and the app has now been renamed Demumu, which Guo said was “cuter.”

“‘Are You Dead?’ sounds more like a joke,” says Lisa Li, a 23 year old English teacher, “But Are You Alive? sounds like you’re rising from the dead and that would be even weirder.”

Li, 23, said she found the app “a bit absurd.”

“I’d be afraid that if I were forgetful and missed a check-in, people would actually think I’m dead,” she said.

She said she thought most people were downloading the app out of curiosity. “Some people really do worry that if they die, no one will find them,” she added, pointing to a recent string of highly publicized cases of young Chinese professionals, particularly at tech companies, dying suddenly after long periods of intense work.

Cui Xiyue, an exhibition planner in Beijing, said she downloaded the app when she was “going through a period of depression and mental health issues.”

“Just getting through a single day back then wasn’t easy,” said Cui, 23.

“When I first got it, I checked in every day, but I didn’t stick with it for very long,” she said. “I probably don’t need it anymore because I’ve stopped thinking about those dark things.”

Loneliness has long been a concern for older people in China, where more than one-fifth of the population is over 60. When younger family members migrate from rural areas to cities, they are often left behind.

But social isolation is also a problem for young Chinese, who are increasingly reluctant to get married and have children amid the rising cost of living and competition for jobs.

Yuying Tong, a sociology professor at the Chinese University of Hong Kong, said she thought the app would be helpful for young people living alone.

“Of course, to some extent they are joking, it’s more sarcastic,” said Tong, co-director of the university’s Centre for Chinese Family Studies. On the other hand, she said, the app could lead people to reflect on their single life.

Some commenters on Chinese social media were skeptical of the app’s usefulness.

“Do people really use apps like this? If I get busy and forget to check in, wouldn’t I end up ‘dying’ every other day?” read one comment on Weibo.

Others rejected the idea of having yet another place to report to.

“You have to clock in for school, clock in for work, and now you have to clock in just to prove you aren’t dead,” one commenter said. “Chinese people — spending a lifetime ‘clocking in.’”

Tong said loneliness was less of a problem for young people than for older people because they are “more adaptive” when it comes to using the internet to connect with the outside world.

“Some of the activities can be transferred offline,” she said, pointing to the thousands of people who showed up in a village outside the Chinese city of Chongqing to help a young woman and her father slaughter pigs for a traditional banquet after she posted a callout last week on Douyin, the Chinese version of TikTok.

“Young people can find a way to overcome their own loneliness,” Tong said, “if they’re really willing to.”

Janis Mackey Frayer and Dawn Liu reported from Beijing, and Jennifer Jett from Hong Kong.