There's a basic problem in the world of mobile app development. 

Developers invest a lot of time and money in creating a great app, and they deserve to be rewarded for that. But consumers are unwilling to pay. As Ryan Chang noted in a tutorial on pricing apps, paid apps only account for a small minority of overall app revenue.

One option, of course, is to offer a free app that includes in-app purchases. But many people hate those too, especially when the demands for money are too intrusive. So what's an honest app developer to do?

Amazon's newly-launched Amazon Underground offers an intriguing solution. Customers get to download and use your Android app completely free, and Amazon pays you for every minute that they spend using it.

Here's a one-minute explanation of how it works:

Customers do get shown some interstitial advertisements, so in a sense this is similar to other mobile advertising models. But what's different about Amazon Underground's model is that developers don't have to worry about setting up ads, or about whether users will click on them or not. 

All that matters is how many people use your app and how long they use it for, so you can focus purely on creating a powerful user experience that keeps people coming back for more. 

You then paid a flat rate per user per minute: in the US, that's $0.0020, and the rates are similar in other countries, allowing for currency conversion. 

Are You Eligible?

Not every app is suitable for Amazon Underground. Because payment depends on active user engagement, a utility app that runs in the background or only gets used occasionally would not be suitable. Also, there are some eligibility requirements:

• Your mobile app must be available for download from at least one other app store, such as Google Play, and be monetized in at least one of the following ways:
  • The app is available for purchase for a fee in all other app stores where it is sold.
  • The app contains in-app items that are available for purchase for a fee.
• Your mobile app must not contain any subscription in-app items.
• The features and gameplay of the Amazon Underground version of your app must be substantially similar to or better than the non-Underground version.
• When you submit your app to the Amazon Appstore, you must make your app available for distribution on at least one non-Amazon mobile device.

Find Out More

If you're interested in learning more about Amazon Underground, you can read the introduction, check out the more detailed guide, or use this revenue forecaster to estimate how much money you might make.