Coupon apps offer easy ways to save money and earn cash back on everyday purchases.

Not all coupon sites are created equal. Some are clunky and contain endless lists of promo codes that never seem to work. Others, however, can make it fast, easy and convenient to find deals.

While the potential upsides may seem clear, it is important to first understand how these platforms work and get a sense of any possible drawbacks. How do cash-back apps work?