Amazon announced today that app downloads from its Appstore grew more than 500 percent in the last year. The phenomenal number is not surprising given the reach of the Amazon Appstore. It’s natively a part of Amazon’s Kindle ecosystem, but it’s also available to Android users as a side-loaded application. However, as noted by GigaOM, it’s most likely the Kindle tablet devices that have contributed most to this number.

In addition to this growth, Amazon announced games made available on the Kindle Fire have doubled since the launch of the Kindle Fire HD. Developers have also been downloading the SDK at double the rate they were a year ago. All this news was slightly downplayed, however, as it was a part of an official press release on Amazon’s new A/B Testing service for app developers looking to distribute their applications via the Amazon Appstore. Amazon cites all of these as reasons developers should look to its digital marketplace as a distribution platform.

To reel in more app developers, Amazon also tacked on a few new features for its developers. There's GameCircle, which will add achievements, leaderboards, and the ability to add friends; a new Maps API, which will be more interactive than its current offerings; and localization support, which will give developers the opportunity to add specific pricing and language options for different regions. The aforementioned A/B testing will also help developers understand what users of the Amazon Appstore and Kindle ecosystem like and need from their applications, as their scope may be increasingly different from that of regular Android users.