India, Jan. 13 -- An app called "Are You Dead?" does not sound like something most people would download willingly. Yet, for a growing number of people who live alone, the bluntly named app is proving to be reassuring rather than disturbing. Its appeal lies not in clever design or advanced technology, but in how directly it addresses a fear many people rarely say out loud.

The app, known as Sileme in Chinese, launched in May and has already become the most downloaded paid app in China. It is aimed squarely at people who live by themselves and worry about what might happen if they fall sick, have an accident, or simply collapse with no one around to notice. For those without nearby family or daily social contact, the concern is not hypoth...