Little Birdie, which launched online today, guarantees customers the lowest prices by providing detailed data on how an item has been priced at different stores.
CEO Jon Beros said the new feature something the online market had been missing.
"We get bombarded by different products, different brands, and we really need the confidence to know that when we make a purchase we are getting that best price," he said.
The website reveals all discounts and price hikes an item has previously been subject to at major retails.
It will also give customers price alerts to let them know price drops are only for a limited time.
Mr Beros said its function was to let customers in on "amazing offers" that retailers didn't always advertise widely.
The website, which holds pricing data for about 70 million products, has been launched by the creators of Catch, formerly known as Catch of the Day.
Catch was sold to Wesfarmers for $230 million two years ago.
Little Birdie has been backed by a $30 million input from Commonwealth Bank.