What is Amazon Underground?
Amazon Underground is an app store and platform developed by Amazon for Android devices. It offers premium apps for free, with the developers getting paid based on utilization. Users can download apps, games, and in-app items without paying anything while Amazon pays developers based on the amount of time a user spends interacting with the app.
The catch is that Amazon Underground apps contain lockscreen ads and ads within the apps themselves. So while you don't pay money, you pay with your time viewing ads. The platform launched in 2015, but has failed to really challenge the Google Play Store in terms of market share or number of apps available. Still, it provides an alternative source of free premium apps for Android users willing to view ads.
Some of the positives of Amazon Underground include access to paid apps at no cost, incentives for developers to make apps with rich content and user engagement, and an app distribution model distinct from traditional pay-once models. Negatives include significant advertising throughout apps, limited global reach focused mostly on the US market, and a still relatively small catalog size compared to alternatives like the Google Play Store.