The total number of active applications worldwide in the Android Market reached the 400,000 milestone, according to app store analytics firm Distimo. Android Market topped the 200,000 and 300,000 available apps milestones in April and August 2011, respectively.

The main contributors to reach this latest milestone were free applications. According to Distimo's numbers, roughly two-thirds of the available applications are free in Android Market. The percentage of free applications has grown month-over-month from 60 percent in April 2011 to 68 percent free content at the end of 2011.

Distimo notes that one of the reasons behind this increase in free content is the success of the "freemium" business model.

Google Android Market needed two more months in order to reach this landmark compared to the Apple App Store for iPhone, which hit the 400K available apps in June 2011.

In addition, to the 400,000 downloadable apps, Distimo reports that Android Market now has more than 100,000 publishers active in its application store. Each developer publishes 4.1 applications on average, while developers published nearly five apps on average a year ago.