Promo code sites have become big business, with digital coupons surpassing paper for the first time in 2020. Major deal sites make millions based almost entirely on commissions from each sale. They don't sell shopper data and it's not a scam. In fact, big companies like PayPal and Rakuten are buying up deal sites for billions. From Honey to Slickdeals, Rakuten Rewards to Brad's Deals, CNBC asked the major sites what it takes to find deals that are real and why the business model works.

With the huge boost in online shopping during the pandemic, deal-finding sites have become a major business. In 2020, Inmar Intelligence found that digital coupons surpassed printed coupons for the first time ever.

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