 Upside is an incredible app for anyone who buys gas, groceries, or dines out. And who doesn't? That's why it's my favorite secret weapon for saving money. I got $10 back on groceries and 55 cents back on every gallon of gas. I even got cash back at Chipotle and Starbucks. Upside is free to use. Just download the app, claim an offer for what you're about to buy, and get paid. Get three times more cash back compared to credit card rewards or loyalty programs.