Tipping is a significant part of culture in the United States. We’re not bound by law to tip, but there’s a social code that compels us to leave a little something when someone helps us out.

“Tipping is built into the American economy,” said etiquette expert and author Juliet Mitchell, who goes by “Ms. J.” “Tipping supplements someone’s salary. ... It can be how people earn a living.”

That may be why it can feel so terrible when we don’t have cash to tip. Not all of us remember to keep small bills on hand or envelopes of $5 bills in our suitcases like some forward-thinking travelers.

Instead, the guilt rises inside us when a valet, bellhop, driver, delivery person or housekeeper does a good job, and we realize we forgot to hit an ATM. That may be a reoccurring discomfort if you’re someone who doesn’t carry cash regularly, which is more common as our global economy becomes increasingly cashless.

You’re not, however, doomed to be that traveler who always skips out on a tip. Here are ways to show gratuity, cashless.

Consider mobile-payment apps

If you don’t have cash but you do have a smartphone, consider mobile-payment apps. Venmo, Cash App, PayPal, Zelle and Apple Pay all offer ways to send money quickly and easily. Some of these companies also offer non-mobile ways to pay online; if your smartphone dies, you might be able to access payment services through a laptop or, in desperation, a hotel computer.

The practice may feel strange — it’s clunkier than handing someone a few bills — but you wouldn’t be the first person to tip this way.

“I’m seeing more and more waiters, entertainers, and other service workers accept Venmo, Paypal, and Zelle for tips — it’s a smart workaround as we become truly cashless,” Molly Fergus, vice president and general manager of the travel planning site TripSavvy, said in an email.

While staying in a resort in Aspen, Colo., this summer, Kathy McCabe, host and executive producer of the PBS show “Dream of Italy,” was about to tip when she got a sinking feeling as she realized: She didn’t have any cash.

“The bell boy had lugged all of our stuff in a golf cart, so I felt extra bad,” McCabe said in an email. “I asked him if he had a Venmo account, and Venmo’ed him the tip on the spot.”

Frank Keller, a senior vice president at PayPal, said that since the pandemic began and some businesses stopped taking cash, the line between physical and digital is blurring even faster, changing the way we shop and pay people.

Keller said PayPal and Venmo have integrated a tipping feature into apps with QR codes. The business owner — say, a tour guide or driver — can open their Venmo or PayPal app, pull up their QR code and have a customer scan with their smartphone to tip.

On PayPal, tips can be given through a separate “Tip Jar” QR code that doesn’t require a purchase to use. On Venmo, users with a “business profile” can turn on a tipping feature. People who are wary about sending money to a stranger through Venmo may feel more comfortable connecting with a business profile.

Fergus said mobile-app tipping methods are sometimes preferred to a credit-card gratuity.

“Remember that credit cards charge businesses a small percentage of every transaction, and for an independent restaurant or shop, this can be a big expense,” she said. “Whenever you’re able, tip in cash, or use Venmo or PayPal.”

See if the hotel, spa or restaurant has a digital tipping option

Some businesses are adding digital tipping services instead of leaving it up to individual staff members to figure out tips.

Chris Chiari, chief executive and owner of the Patterson Inn in Denver, said the boutique hotel has seen interest from guests to have cashless tipping available at checkout. They’re working to make it happen, but the service has proved tricky to implement.

“We’ve considered Apple Pay among other cashless trends but are ultimately overwhelmed by the variety of options and do not want to overwhelm the guest,” Chiari said in an email.

That is where companies such as TipYo and TipX come into play: They work directly with businesses instead of targeting tippers.

An avid traveler, Brian Walsh founded TipYo after repeatedly being without cash to tip while on the road.

“Nine out of 10 times, I didn’t have cash,” Walsh said. “I thought it was insane I can’t give gratuity by phone.”

TipYo launched in 2019, offering hotel brands a way of incorporating secure digital-tipping options into their app or website. In May, Virgin Hotels became the latest to sign on, using TipYo technology through its app Lucy. Virgin Hotels guests can use the Lucy app to tip specific staff members, such as housekeeping or bellhops, throughout their stay.

A contactless tipping concept that launched during the pandemic is TipX. Unlike most mobile-payment apps, TipX doesn’t require users to download an app. Customers scan a QR code at the business and select a specific employee to tip. The full tip goes to the employee, and you can leave confidential reviews.

TipX is at four hotels and a few businesses in Texas and Florida so far, but the company hopes to expand into sectors such as valet services, public and private transportation.

Tip with gift cards or crypto

If your wallet only holds cards and no cash — or you’ve switched to a digital wallet completely — carrying around bills becomes an even bigger hassle.

At the Driskill Hotel in Austin, director of sales and events Ashley Famalette said that while Venmo is a popular way for guests to tip, she has also seen guests carry gift cards for services such as Uber and DoorDash in lieu of cash tips.

If you’re paying for a service with a gift card, keep in mind that not all gift-card transactions allow for tipping, Mitchell said. Before the business runs the card, ask to add tip.

For cryptocurrency enthusiasts, there are ways to tip with their preferred coin. Some options go through custodial wallets, which are mobile payments verified by PIN. Twitter even got into the mix in September with the launch of Tips and allows tipping through several methods, including bitcoin, via the interface Strike.

When you tip is changing, too

While it may feel like tipping is becoming more widespread thanks to digital payment systems, it’s falling off where most of us do it most often — restaurants.

A growing number of people in the hospitality industry have been pushing toward eliminating the customer-controlled tip in favor of incorporating a service charge into the check. The service-charge movement accelerated during the pandemic as restaurants re-engineered their operations to survive with fewer customers.

The restaurant Leah & Louise in Charlotte said its 23 percent service charge improves employee benefits not only for servers, but also kitchen staff and management. The charge, which it calls the BayHaven Pledge, helps pay for things you would expect from most careers, such as health insurance, paid time off, a 401(k) match and a holiday bonus.

On the customer side, the pledge takes out the guesswork and eliminates one more place you have to worry about tipping — in cash or otherwise.