There are a lot of apps floating around on the Amazon Appstore that are labelled as 'free' but end up urging you to make in-app purchases. In response, Amazon has launched Amazon Underground, a shopping app for Android devices, to offer apps that are absolutely free with no hidden costs thanks to a deal its doing with developers.
Amazon Underground is made possible through a deal with third-party developers to waive the cost for a collection of apps, games and in-app purchases worth over $10,000 through the standard Amazon Appstore:
We're paying them a certain amount on a per-minute paid basis in exchange for them waiving their normal in-app fees. To be clear, we're the ones picking up those per minute charges so for you it's simply free. Just look for apps and games marked with an "Actually Free" banner.
You can't get Amazon Underground on Google Play because, you know, it's kind of a competitor service. To download the Amazon shopping app, go to www.amazon.com/underground on any Android browser. From there, you can download the APK directly onto your Android phone and it will guide you through the installation process, which requires you to allow unknown sources.
Incidentally, Amazon Appstore has removed its Free App of the Day feature but hey, at least now we have Underground.
[Via Amazon Underground]