Now expanding globally and adding new features.
More than 1.4 million people have downloaded retailer H&M's iPhone app in the eight weeks since its release.
The app lets users browse the retailer's current range of clothing, find their nearest store, and get a discount m-voucher by shaking their handset when the app is running.
UK studio ustwo developed the app for H&M, and has been updating it regularly with new content and campaigns.
The app is also being launched outside the UK, matching H&M's international expansion.
Early next month, an update will introduce Twitter sharing, as well as the ability for users to check the balance on their H&M gift cards.
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However, it's the 1.4 million milestone that will make rival retailers prick up their ears (and double-check their app marketing budgets).
"This astounding figure represents true brand power and can be put down to H&M's continued investment in mobile," says ustwo co-founder Mills.
"Giving users what they want with ongoing and relevant updates is a surefire way to keep them engaged, telling their friends and coming back for more."
