I’ve recently been earning Amazon gift cards utilizing Perk Rewards on my phone and tablet.
You can view the site with your computer, sign up, and check out different apps. They offer iOS and Android apps/games through which you can earn gift cards and have the opportunity to win other prizes.
It’s free to sign up, and of course they’re making money via advertisements but as long as we’re getting a cut, I see no issues with it.
Payment proof right here: