Although Instagram was the best-known of the photo manipulation and sharing apps even before its billion dollar acquisition by Facebook, it has remained far from alone in the market. In the Apple App Store there are screens full of picture editing, photo sharing and camera apps.

Most of these apps are ignored by iPhone users, but, some succeed even without spending on media and user acquisitions. FilterMania 2 from Israeli company Dropico Mobile was downloaded over 1million times in six days while 22 million filters were downloaded, according to The Next Web.

This made it the second most popular free photography app in the US, and the first one in over 30 countries. In total, FilterMania 2 reached the Top 25 for apps from all categories in over 50 countries, Dropico says.

So what is the secret of the app’s success?

Partly, it seems, there was an existing user base from the first version of the app. They were able to say what they wanted, which was ease of use, both in creating images and then in sharing them. Users enjoy sharing and, of course, it is naturally viral. With over 300 free filters to choose from, FilterMania 2 is also more adaptable than Instagram.

Dropico’s CEO Gabi Ben Ami said:

“Our goal was to create an app that let users express their artistic side, effortlessly. Based on the initial feedback we received, users were blown away by what they were seeing. The realistic photo filters we introduced ignited user creativity, that goes above and beyond color based filters. It’s about artistic expression, just as our tagline says: Turn your iPhotography into Art.”

So success comes from creating the app your customers want, then providing the means for them to tell their family and friends about it. Simple. (Copyright © Dow Jones & Company, Inc.) 06/22/12)