When a mysterious Taiwanese company took $127 from Juan Mackie's bank account, alarm bells sounded.
The 24-year-old has never been to Taiwan.
"With a bit of investigating, I found out they were fraudulent," he says.
He cancelled his card and is awaiting a refund from his bank. Yet the credit, he says, goes to an Australian app called Pocketbook.
The spending-management app, which boasts some 50,000 Australian users, is forging a reputation for helping catch out fraudsters.
The app pools a user's various bank accounts, providing a single view of all spending. Regular transactions such as rent and weekly groceries are categorised, meaning irregular transactions immediately stand out.
In October, Pocketbook helped finger a card-swiping scam when 10 users reported suspect transactions from a deregistered NSW company after paying taxi fares with their credit cards.
"It's magic," Mackie says.
On Friday he thanked the team behind the app in a Google Plus post. They investigated the fraudulent transactions to gauge whether others had been affected.
By Monday, Pocketbook had issued an alert on its website urging users to watch out for any payments from a Taiwanese payments processing company called Neweb Technologies, typically for 1150 Taiwanese dollars or about $AU45, depending on the bank's transaction fee.
Victims may have recently made online purchases or used their card in Asian countries such as Singapore or China, the warning says.
"As an organisation, we can be a lot quicker than banks in responding to fraudulent payments," says Pocketbook co-founder Bosco Tan.
"We provide all the avenues for users to tell us when things aren't right, so we can quickly look through the database to see if anyone else is affected and get a response quickly.
"We can be responsive in that regard and I don't think the banks are equipped to do that."
Pocketbook users, he adds, are far more likely to recognise fraudulent transactions than occasional netbanking users.
"People generally aren't critical when they look at their netbanking statements.
"They look at it with more of a time gap and it's not part of their daily experience."
Pocketbook also lets users set daily "safe spend" limits, which raise immediate alarm bells when breached.
The company has informed the federal government's scam watchdog, SCAMwatch, of the fraudulent payments.
