I have no idea how to describe these sites, so let's just say they give you a shopping list and you get cash back if you buy any of the items and take a picture of the receipt. Really, it's easier than it sounds.
Note: The sign-up link below earns me $1. Yes, a whole dollar! If you use it, it would make me happy.
Snap by Groupon is better than Ibotta and as good as Checkout 51. There are 42 items on the list this year, including a lot of unbranded options (e.g., You get $1 cash back for buying any gallon of milk, $1 for any bag of candy, $.25 for kale, $.50 for toothpaste and $.50 for apples.). There's also cash back for certain branded products, such as $2.00 back for Huggies wipes or $1.00 for Barilla pasta. Added bonus:You can do some offers more than once.
Since many of these products advertise on different sites, there is a good chance that they will be on more than one site and you can double or even triple your rebate on the same product.