Enter Josh Rowe and RealAs, a website and app built for house-hunters who want to know the real value of a property. Using an algorithm developed by machine-learning and data-mining academics at RMIT University, RealAs claims to predict property values with a 5 per cent rate of accuracy.

Chief executive Rowe says even he was initially sceptical of the science behind the predictive algorithm.

"I didn't believe the algorithm at first," he says. "I literally thought that I was just applying some sort of percentage on top of the figure.

"It wasn't until I went to an auction in my suburb. The house was listed for $600,000 – RealAs predicted $680,000 and it sold for $690,000.

"RealAs predictions keep changing over time and they include sales data and current market data."

The business was launched in August, but has already won a major innovation award, including a $40,000 cash prize.

RealAs won the Westpac Innovation Challenge in November – a joint competition run by Westpac and venture technology accelerator BlueChilli.

Westpac head of digital business banking Kalpana Gee says RealAs has the potential to disrupt not only the resident property market, but the commercial property market too.

"This is exactly the kind of leading-edge, future-ready idea we were looking for," she says. "It has the potential to completely change the way our commercial real estate customers do business."

The $40,000 prize will be used to create the RealAs app for Android devices; the six-month placement in the BlueChilli accelerator program will help to further develop its website and app.

Rowe says the start-up's quick success has its investors hopeful of a global expansion.

"We'd love RealAs to be the TripAdvisor of real estate … a platform where people can have discussions about property. We'd love to expand globally. A few people have emailed us from the US to ask us when we're bringing it over there."

Overseas competitors include US online sites Zillow and Trulia, which both offer more than just property valuations: both sites provide property sale listings, financial calculators, mortgage rates and information articles.

Locally, RealAs takes on the likes of online property giant REA Group, which operates realestate.com.au.

But the start-up has a long way to go – it attracts 10,000 unique monthly visitors; realestate.com.au gets 40 million monthly visits.

REA Group chief product officer Henry Ruiz says online real estate businesses have empowered homebuyers, making them better informed and more confident to buy.

"Technology has had an enormous impact on the real estate market," Ruiz says.

"Early on, we realised that the desire of everyday Australians to consume real estate content in a digital format was only going to grow, especially as data bandwidth and speed improved over the years."

RealAs is already making money from advertising on its site, but Rowe says it has yet to break even on its $500,000 capital investment. However, the start-up's investors are aiming to turn a profit within the first 12 months.

RealAs is free for all users, who just need to register an email address and log in. Rowe says there are no plans to change the free-for-all model, but there are plans to launch an investor version in the future.

RealAs was founded by veteran buyers' advocate David Morrell, a vocal opponent of underquoting by dodgy real estate agents. He is joined by three others on the board, including Rowe and Hawthorn Football Club president Andrew Newbold.

Experienced Melbourne real estate agent Greg Hocking says the site is sure to change Australia's real estate market.

"David's been a real crusader over many years and he's taken his app to further his aims to, in his own sweet way, tidy up underquoting," he says.

"Underquoting is the bane of many buyers' lives. It's something the authorities and government bodies have basically failed to do."

Predicting sales prices isn't an exact science, which means some properties are inadvertently underquoted by agents, Hocking says.

"David's app wouldn't go anywhere helping people on those sales, but as a guide it's helpful."