Supergeek David Whitehouse, whose Trolley Checker website helped to bring down Tesco’s ill-fated Double the Difference campaign last year, is gearing up to launch a smartphone app version of the website.

The Martin Lewis disciple, who guided hundreds of forum members on the MoneySavingExpert website to refunds of over £100 from Tesco under the short-lived promotion, said the app would save shoppers at least 10% on the weekly shop. “It will allow shoppers to scan the barcodes of the items they are buying and separate them into two transactions, the items that are cheapest in the supermarket you’re in and the items that are the same price or cheaper in one of the other supermarkets,” said Whitehouse. “Splitting your shopping in two allows you to make a saving on your groceries of around 10% on average using the price match schemes.”

The original trolley Checker website also now features Sainsbury’s, as well as Tesco and Asda.

“With Sainsbury’s now doing brand matching, I have included them at the same time,” said Whitehouse.