OneOpinion— signing up is completely free, as it should be. This survey site, like many others, works on a points system: 1,000 points = $1. Once you reach 25,000 ($25), you can choose to cash out via PayPal or an Amazon gift card. OneOpinion also offers product testing, which means you have the opportunity to test new products at home before they hit the market.
What’s the catch? None, really. Cash back apps act as affiliates for many online merchants, which means that whenever you make a purchase through one of the apps, they get a small commission — but then, they give you a portion of that commission as “cash back”. For example, if I buy a pair of Nike shoes through the Ebates app (or website) and spend $75, Ebates may get a $10 commission but then they’ll pass $7 back to me. It’s basically a way to get sale prices on stuff that isn’t on sale!