When Open Garden launched its new anonymous messaging app FireChat in iTunes last week it expected to draw some attention, but its creators were shocked by just how much attention it got. As of Tuesday, FireChat was being download from the App Store more than 100,000 times a day, adding 1.14 new users a second, Open Garden told Gigaom.

Currently Open Garden is the No. 12 app in the U.S. iTunes charts in the social networking category, wedged in between over-the-top messaging giants Viber and Tango, but it’s doing much better internationally. At various points this week it was the No. 1 iOS social networking app in Australia, Chile and Taiwan and No. 2 in Belgium, Israel, Norway and Sweden. The company wouldn’t reveal its download totals since launch, though, saying it’s holding onto that data point for competitive reasons.

“It’s doing very well and we’re almost overwhelmed by the…