App downloads in Amazon’s Appstore have grown by more than 500% year-on-year, the company has revealed.

The company also said that the number of developers with in-app purchasing incorporated in their apps more than doubled in the third quarter of 2012, while in October 23 of the top 25 grossing apps on the Appstore used the same in-app purchasing technology.

The company revealed the figures as it announced the beta launch of a new A/B Testing capability for Kindle Fire developers, allowing them to test simultaneous treatments of their apps, receive data about what has worked best and adjust their apps to take advantage of this customer learning.

“Apps are living products continuously being updated, modified and improved, and with millions of potential active users, developers know that seemingly small changes can have a large impact on customers. Our A/B Testing service is essential for developers because it will help offload the overhead costs of building, maintaining and running scalable tests,” said Mike Frazzini, director of Amazon Games.