Amazon is piloting in-app purchases for titles downloaded from its Appstore, Bloomberg is reporting. The news comes courtesy of fitness app developer Skimble, whose CEO Maria Ly said that the service is currently in testing, and similarly to Apple and Google's systems allows users to purchase both add-ons and subscriptions that expand the functionality of their app. Developers will pay Amazon 30 percent of the revenue generated by each in-app sale — the same cut as full-blown app sales, and matching the rival Google Play store.

However, since the Kindle Fire is a totally locked-down system, for developers wishing to offer subscription models it could be the most convenient choice. As Ly told Bloomberg, "we really wanted to attack the Kindle Fire market, but also have access to the payment methods that support our business." Amazon is yet to comment on the system, and there's no word from any other developer, which makes the scope of the pilot scheme unclear.