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Roc Wong’s supermarket pricing app has become super-popular. (Photo: Supplied / Design: Tina Tiller)

BusinessFebruary 10, 2023

He built a hit app in his spare time. What does he do with it now?
Roc Wong’s supermarket pricing app has become super-popular. (Photo: Supplied / Design: Tina Tiller)

Roc Wong’s supermarket price comparison app has thousands of daily users. But it’s ‘just one man’s side project’ – and now he’s facing a dilemma.

A few days ago, Roc Wong got an email. It was from one of the many users of his app,, which charts supermarket prices across the country. Built in his spare time during three months of 2021, then rebuilt in a frenzy in early 2022, Wong’s seen support grow as consumers search for ways to cope with the cost of living crisis.

But the app’s creation, and its on-going upkeep, takes a toll on the father-of-two. He already has a day job as a software developer, so Wong’s app is run purely as a hobby. “I burn all the midnight oil,” he admits.

The note was from a user who’d received a suspicious email from someone purporting to represent Wong’s app. It looked dodgy but seemed plausible, offering free grocery vouchers from a domain name remarkably similar to his. Wong had nothing to do with it. Immediately, he plugged a note onto his homepage to warn users. “Grocer didn’t and won’t send any emails from ‘’ on ‘free grocery vouchers’,” he wrote. 

His design being used for a scam is a sign of just how popular has become. As rising inflation and the ongoing supermarket duopoly continues to put a dent in pockets, shoppers are desperate to save every cent they can on food costs. Some have turned to co-ops, others have bought  backyard chickens. Those happy to brave Westgate have signed up to Costco and committed to buying in bulk.

Even Wong’s feeling the pressure. He lives in Hobsonville and has a brand new New World supermarket within walking distance, but instead drives to Pak’nSave Westgate, where he walks around with his trolley and scans barcodes into his phone to make sure he gets the best deals. Lately, he’s noticed a 10kg bag of rice, a staple at home with his family of four, sometimes costing as much as $60. It used to cost him just $30. charts the cost of rice, and much more. The free app isn’t slick it stays live thanks to the support of sponsors and Wong’s weekend tinkering but it does the job. Right now, users can track the price of most items on supermarket shelves. Those differences can be steep: Anchor Butter costs $6.50 at Mt Eden Countdown but $8.49 at New World Victoria Park, while Granny Smith apples cost $4.79 per kilo at Pak’nSave but $6.79 at New World.

Like Gaspy, a petrol price comparison app, fans love and rave about the savings it can deliver. “This is a brilliant app that I’ve been using since its inception,” writes one user in a five-star review on the App store. “Sometimes I have found more than $5 difference in prices … for the same product,” says another. “I”m so happy!” declares a third.

As a result, Wong has become a familiar media presence, fronting up for major interviews about his creation. In some of those chats, he’s treated as a spokesperson against the duopoly, or asked questions about inflation. But he’s not trying to fight supermarkets, and building didn’t come from a place of anger at rising food costs.

Instead, like the tech engineer that he is, he just wanted to solve a problem. He puts it like this: “I’m just an engineer building a potentially useful tool. I’m not fighting with supermarkets. I don’t have the power to do that. I’m just trying to make my life easier. As a result, he hopes everyone can make educated purchasing decisions at supermarket check outs. “That’s pretty much it.”

Making an app is not easy. It requires persistence, dedication and commitment to iron out a never-ending and ever-evolving list of bugs. Wong estimates his first go at building took him up to 300 hours. It didn’t work. When he made a list of his 2021 New Year’s resolutions, he decided to have another go, and managed to launch it in April, 2022. It quickly took off.

Now, has thousands of daily active users. All those users means his app needs constant upgrades. Wong already has a day job as a software developer for emergency departments in the United States. So, in the evenings and on weekends, he works his way through a long list of plans. He’s due to add Supie, the online-only Auckland grocery service, to his platform soon, and wants to build the ability to highlight some of the week’s best deals. (Wong’s data, scraped from online supermarket stores, was used to create last year’s cheese tracker on The Spinoff.)

It’s all on him. “It’s just one man’s side-project,” he says. “It’s very limited.” Among his five-star reviews are ideas sent from fans. “It would be nice to be able to share [shopping] lists,” requests one. During our interview, I jumped in too, asking if could provide historical data tracking price rises. Wong’s response? It could, yes, but, “I just don’t have the time to do it all.”

It’s getting to the point where the offers he keeps getting to buy it, or help him build it into a fully functioning commercial product, are becoming tempting. Wong’s already turned down one offer to buy it for $10,000 because “it felt too low”. Aside from sponsors, he’s refused all offers of outside help. “I’m still on the fence about how to bring other people in to help with this project,” he says.

Talking to The Spinoff during his lunch break, you can hear Wong working through his options. He likes his creation and the fact that it’s all his, but he’s reluctant to quit his day job for the uncertainty of start-up life. So far, the app hasn’t made him any money.

So, for now, Wong will keep running from his Hobsonville home, snatching spare moments from family life to upgrade it, keep it running, and turning down those medium money offers. Just a month ago he made another New Year’s resolution to try and inspire himself. “I was a bit slack before Christmas,” he says. “My New Year’s resolution is to improve it, or commercialise it.”

His voice trails off. Which one will he choose? “I don’t know.”

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