Consumer Reports Money Adviser took a look at several to see if you really can leave your wallet at home.
Maryssa Menkin is paying for her salad using Square Wallet's free application. The digital wallet app links to her credit card, which she finds very convenient.
"I hate carrying a lot of things and, you know, I find that I do always have my phone on me. So it's just very simple," she said.
Starbucks is one of the hundreds of thousands of businesses nationwide that have signed up for Square Wallet.
Square is compatible with a number of iPhone and Android models, and Consumer Reports Money Adviser says it's pretty easy to use. But other digital wallets are not as widely accessible.
"For instance, Google Wallet and Isis aren't available on iPhones and only work with some service providers. They also require a wireless technology that only some stores can use," Amanda Walker, Consumer Reports Money Adviser, said.
And some digital wallet apps will only link with a few credit cards. So you may need to link to a prepaid card, which can incur additional fees.
And that may also mean you don't have the best protections if you lose your phone or someone breaks into your account.
"Prepaid cards, whether in your hand or on your phone, have no guaranteed protections against unauthorized transactions, so you could lose whatever balance is on the card," Walker said.
Still, if, like Maryssa, you like leaving your bulky wallet at home, Consumer Reports says use an app like Square that links to a credit card for the best consumer protections.
Consumer Reports says be sure to report a lost phone or suspicious activity to the credit-card company right away. And of course also inform your cellular carrier, so it can disable the phone.