Unlike some other cash back apps, Checkout 51 features grocery offers that aren’t store-specific. You can browse and choose offers within the app and then upload a photo of your receipt to verify your purchase. In fact, the process is nearly identical. If you’re a Fetch Rewards user, you’ll immediately understand how Checkout 51 works. Like Fetch Rewards, Checkout 51 is a simple cash back app that rewards users for grocery shopping, gas purchases, and online purchases. Best Apps Like Fetch Rewards for Cashback and Rewardsīest Apps Like Fetch Rewards for Cashback and Rewards 1.