It’s a shopper’s nightmare: Buying something, then seeing it cheaper at another store. Thanks to price-comparison apps, there’s no need to guess if you’re getting the lowest price.

All you need is a smartphone and some downloaded apps. Smartphone owners have been using the price-comparison apps for the past couple of years. But they’ve improved a lot recently. They’re faster and easier to use than earlier versions. -- Joseph Pisani, AP business writer