A new report suggests that nearly two thirds of apps in Apple's iOS App Store have no downloads, no ranking and are invisible to users.

GigaOM reports that Adeven, a German mobile analytics and ad verification firm, has used a new tool to calculate that 400,000 out of the 650,000 apps on the iOS App Store are 'zombies'.

The firm's Apptrace tool launched this week, and has revealed that, although Apple boasts of the 650,000 apps on iTunes, almost two out of every three are dead in the water.

Christian Henschel, CEO of Adeven, told GigaOM: “The reality is there are only a couple of thousand apps that really make some kind of downloads. This is based on Apple's closed system – it's touch to discover those kinds of apps.”

“You don't have a proper search, so the only way to discover new apps is through the top listing,” Henschel continued. “If you're not on those lists, it's not sure that you're being discovered by anyone else. The top 25 tend to be the same companies who spend millions of dollars to get to the top of those lists. If you're an independent, small app publisher, then it's really tough to be discovered. 

The App Store has, however, seen some improvements in its search algorithms recently, a change that is believed to be the result of Apple's acquisition of app search company Chomp in February.

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