Consumers interested in using Amazon Underground could download the app from the Amazon website.8 The app could not be downloaded from Google Play, Google's Android app store, since it violated the conditions necessary to be listed in the app store.910
Once the consumer had downloaded Amazon Underground, they could download all apps participating in Amazon Underground from within the Amazon Underground app. In addition to being able to download the app for free, the consumer could also make in-app purchases for free.
An app creator could choose to participate in the Amazon Underground program. The app creator received payment based on the time spent by users in the app after downloading it, at a flat rate of $0.002 per user minute in the app.11
Amazon listed the following eligibility requirements for participating apps:
Amazon advised against using Amazon Underground for the following apps:
In addition, Underground was not recommended for modified versions of an app that removed in-app purchases, or that modified their gameplay by removing in-game currency, or premium apps whose only premium feature was being ad-free.
Amazon paid app creators based on the total time spent by users in the app, at a rate of $0.002/minute.1213 In order to monetize Amazon Underground, Amazon showed ads when a user first downloaded an app, and occasionally on each subsequent opening of the app.14
Amazon Underground launched on August 26, 2015, and Amazon simultaneously retired its daily free app program.15161718
In March 2016, Amazon reported some statistics on the growth of Amazon Underground, leading to renewed media coverage of Amazon Underground.1920
In April 2017, Amazon announced the program would close to new apps at the end of May 2017, and shut down completely in 2019.21
Amazon Underground was criticized for being much smaller than the Google Play app store, making it of limited utility as a standalone source for getting games.22
Goat Simulator performed well on Amazon Underground, leading Wired writer Brian Barrett to argue that the lack of need for payment may have made the app particularly appealing to children, for whom even a small amount of money requires parental consent.23
Amazon Underground was praised for helping developers focus on creating engaging in-app experiences rather than worrying about monetizing through in-app purchases. It was also praised for helping all developers make money right off the bat in direct proportion to usage, compared to the in-app purchase model that only some kinds of apps could make significant money off of.2425 Commentators compared it to the Kindle Unlimited plan where Amazon allows readers to read books for free from a diverse collection of authors and then pays authors based on the fraction of their books read.26
A report by IHS Technology highlighted the following key challenges for Amazon Underground:27
"What's New with Amazon Underground?". Amazon.com. Retrieved April 26, 2016. https://developer.amazon.com/public/solutions/underground ↩
Moscaritolo, Angela (August 26, 2015). "Amazon Underground Offers Apps That Are 'Actually Free'". PCMag. Retrieved April 26, 2016. https://www.pcmag.com/article2/0,2817,2490149,00.asp ↩
Barrett, Brian (August 29, 2015). "Has Amazon Cracked the Problem With In-App Payments?". Wired Magazine. Retrieved April 26, 2016. https://www.wired.com/2015/08/amazon-underground-in-app-payment/ ↩
Lowery, Victoria (March 15, 2016). "Will Amazon Underground Change Revenue Model for Developers?". Inquisitr. Retrieved April 26, 2016. http://www.inquisitr.com/2892375/will-amazon-underground-change-the-revenue-model-for-app-developers/ ↩
Johannes@Amazon (April 28, 2017). "Underground Actually Free Program FAQ – 2017 Update". Amazon.com. Retrieved May 18, 2017. https://forums.developer.amazon.com/articles/69139/underground-actually-free-program-faq-2017-update.html ↩
"Amazon Underground". Amazon. Retrieved April 26, 2016. https://www.amazon.com/Amazon-com-Amazon-Underground/dp/B004GJDQT8 ↩
Brewis, Marie (August 27, 2015). "How to get genuinely free Android apps and free Android games". PC Advisor. Retrieved April 26, 2016. http://www.pcadvisor.co.uk/how-to/google-android/how-get-genuinely-free-android-apps-free-android-games-3623997/ ↩
"Understanding Amazon Underground". Amazon.com. Retrieved April 26, 2016. https://developer.amazon.com/public/solutions/underground/docs/understanding-amazon-underground ↩
Dillet, Romain (August 26, 2015). "Amazon Underground Features An Android App Store Focused On "Actually Free" Apps". TechCrunch. Retrieved April 26, 2016. https://techcrunch.com/2015/08/26/amazon-underground-is-an-android-app-store-with-only-actually-free-apps/ ↩
Singleton, Micah (August 26, 2015). "Amazon launches Underground to promote free apps and games. The Free App of the Day program has also come to a close". The Verge. Retrieved April 26, 2016. https://www.theverge.com/2015/8/26/9210071/amazon-underground-free-apps ↩
Barrett, Brian (April 9, 2016). "Amazon Underground, a New Kind of App Store, Is Blowin' Up". Wired Magazine. Retrieved April 26, 2016. https://www.wired.com/2016/03/amazon-underground-growth/ ↩
Kent, Jack (October 7, 2015). "Amazon Underground innovates with free apps but faces challenges". IHS Technology. Retrieved April 26, 2016. https://technology.ihs.com/550085/amazon-underground-innovates-with-free-apps-but-faces-challenges ↩