Adam has discovered how to 'game' Australia's biggest supermarkets

Using the extension, shoppers can see pricing patterns for items such as dishwashing tablets, muesli bars and yoghurt which alternate prices almost weekly.

It’s a simple system of half-price every second week, Williamson told 9News.

“You’re looking at double the cost if you get it on the wrong week,” he said.

“Or as Coles and Woolworths like to say … half price if you get it on the right week.”

Retail analysts have pointed out some Australian states have legislated price transparency for products such as petrol and say these rules should apply more broadly.

“Maybe we should see something similar in groceries, where supermarkets are forced to share this data with third party developers and we could have dozens of apps like this,” finance expert and Easy Money author Joel Gibson said.

William said he plans to keep improving his plug-in and keep it free to demystify the seemingly unpredictable pricing strategies of our nation’s biggest retailers.

“I’ve learned about everyday low price, high low pricing, a shallow sale versus a deep sale,” he added.

“It’s really insightful and these are the sorts of things I’d like to surface with consumers so they can make better buying decisions.”