If you want a site where you can save items you want to buy and get notifications when they're in stock or on sale, Karma is a good option. It's got a browser extension and mobile app that can help you shop online by automatically applying promo codes and cashback rewards at checkout. It also offers features like price alerts, product comparison and centralized wish list management. Karma covers more than 100,000 stores and more than 6 million people have used it, saving an average of 18% per purchase.
Another contender is Beni, an AI-powered shopping assistant that lets you buy secondhand items from more than 40 resale sites at a discount. Although it's geared for sustainable shopping, Beni also offers price comparison, favorites and alerts. It works on desktop and mobile, and it's free to use, though it makes money through affiliate marketing, covering more than 2,000 retail sites, including Gucci and Target.