SEOUL: Throngs of people have been milling seemingly aimlessly around the forecourt of a museum in central Seoul, brushing silently past each other with heads bent toward smartphones while fingers frantically tap screens - in the latest money-making trend.

Walking 10,000 steps, completing tasks such as subscribing to social media, or just tapping the screen when other users are nearby can generate up to 10 cents a time for users of financial services app Toss from South Korean startup Viva Republica.

The viral campaign has seen Toss become a frontrunner in a trend where businesses win users through cash- and points-offering loyalty apps, which have risen in popularity in an economy with high youth unemployment and surging inflation.

As many as three in four adults earn cash through such applications, showed a recent survey by job portal Incruit.

"I've only made 150 won (US$0.11) so far, but I plan to continue so I can buy coffee or pay for something using the app," said 27-year-old office worker Baek Na-young.

Some 4.4 million users have used Toss' cash-giving in-app feature since its January launch, and the number of times people open the app on handsets has increased 30 per cent, Viva Republica said.

Retiree Han Sun-jae, 77, said he had made some 50,000 won so far through the Toss app.

"My daughter works nearby and told me many people were gathering here, and that I could make more money here," he said outside the Seoul Museum of Art, where office workers gathered at lunchtime based on rumour and grapevine chitchat.

The trend shows people are going the extra mile to help overcome an increasingly dire economic situation, experts said.

The consumer inflation rate hit 5.1 per cent in 2022, the highest since 1998, with food and transport prices up 5.9 per cent and 9.7 per cent respectively.

Some 497,000 people aged 15 to 29 in February said they were on a break from employment and not actively seeking work, showed Statistics Korea data, the most since records began in 2003.

Some experts cautioned that exchanging data for the opportunity to earn pennies could involve sensitive personal information being shared with third parties.

"While the effort to make pocket money is commendable, it could also leave people vulnerable to personal data use," said Lee Eun-hee, a consumer studies professor at Inha University. "It would be wise to consider both sides of the coin."