Dominique Williamson, 23, never had trouble making friends. “I have never been in a position where I didn’t have any girlfriends, to hang out with at least,” she said.

But Ms. Williamson, who is a vegan chef and sells cookbooks, moved to Atlanta from New York City just before the pandemic. When things were still open, she would dine alone and introduce herself to anyone else sitting alone at the bar.

But once Covid-19 hit, that option dried up. The few friends she had from growing up in Atlanta all moved away for jobs, graduate school or because of the pandemic. “I am a creative. I work from home, how do I make friends?” she said.

For most of last year, no one was doing anything fun. But now that cities are reopening and vaccines are widespread, she wanted to reclaim a social life. So three weeks ago she Googled “Making friends in Atlanta.”

The search led her to a Facebook group named Friends in Atlanta with over 13,000 members. It operates similarly to a dating app: participants, all female, post photos of themselves along with a description about what they like to do, and other members can message them privately if they are interested in meeting.

Kourtney Billups, 23, a nurse, reached out, and they agreed to meet for Sunday brunch in early May. “I am on the dating apps as well, so I kind of looked at it as the same kind of thing,” Ms. Billups said. “We bonded right away. We have the exact same chart as it relates to astrology.”

When both realized they wanted to spend Memorial Day weekend in Miami, they booked a trip — flights, hotels, restaurant reservations — on the spot.

Across America, many people are emerging from the pandemic with a diminished social life. Some people moved when gathering places were shut and didn’t have an opportunity to make or nurture new friendships. Others stayed put only to watch much of their network flee.

Now they are turning online to Facebook groups, Meetups and apps like Bumble BFF, where they can connect with potential friends just as they might dating partners. Some more-established clubs and groups, like Soho House, are helping their members, desperate for human connection, to more easily meet one another.

“Who knew making friends as an adult during the pandemic would be so hard to navigate?” Ms. Williamson said.

The search for friends can feel like a full-time job.

“I had a system for it,” said Stephanie Stein, 35, a single lawyer who moved to Manhattan in March 2020 after living in Florida for 10 years. “I needed a brunch friend, a going out friend, a fancy friend to go shopping with, a worker bee friend. I had buckets that I wanted to fill.”

So she got to work, swiping away on Bumble BFF. Her matches had to be female, single and looking like they were having a blast in all their photos.

Ms. Stein found the process to be more liberating than dating. She didn’t care what their jobs were, where they lived or if they were hot. The “friend” dates did not carry the same expectations. “Even if you go on a date, and you don’t like him, but he never texts you, your ego takes a hit,” she said. “With a girl it’s like we are having a bite to eat, it’s fine if I never talk to her again.”

Now she has five or six friends she sees regularly, just as New York City reopens. “We go to dinner, we go to brunch, we all went to a Kentucky Derby party,” she said. “It’s the same as what you do with regular friends. These are my real friends now.”

Some people are turning to Meetup or Facebook.

Nick Yakutilov, 29, a consultant who lives in the Forest Hills neighborhood of Queens, started a Meetup in April called New York In-Person Hangouts for group dinners and comedy shows. “People seemed eager to come out and meet each other, so I thought why not start a group?” he said. It has 500 members and each event (a dinner reservation for 10 people, for example) has sold out within two or three days.

Michael Wilson, 36, works as an industrial engineer at Boeing in the Seattle area, and runs a Facebook group called Making Friends in Seattle!, where people post things they want to do with new friends like hiking. Before the pandemic it had 700 members. Now it has 8,000.

“Every day we probably have a few dozen requests to join,” Mr. Wilson said. “We’re talking about doing a lazy river trip for everyone or maybe Go Karts.”

Members’ clubs that at one time might have been considered standoffish are now helping socially eager members connect. Soho House recently added a feature on its app called House Connect that matches up members based on mutual interests, professional pursuits and answers to questions like “What Keeps me busy.”

Other people are finding friends in less structured ways.

Molly Britt, 38, a content creator for Chevron, lives outside of Seattle. She moved there just before the pandemic with her husband, but they are now separated. With few friends, she felt alone. “The pandemic hit, and I was like, ‘What am I going to do here?’” she said. “I am as extroverted as they come.”

Then a new friend showed up on her actual doorstep.

Michelle McKinney, 46, left her job during the pandemic, and was delivering groceries for Safeway on the side. She rang Ms. Britt’s door, and the two started chatting. Soon it turned into talks about their children and their lives… and how they both wanted to meet new friends.

“She stood on my doorstep for like 30 minutes,” Ms. Britt said. “At some point she was like, ‘I guess I better get back to delivering groceries, but before I go, can I please get your number.’ We immediately started sending each other GIFs that were like, ‘Did we just become best friends?’”

Now that they are both vaccinated, the friendship has moved indoors. “Last week she showed up at my house with pizza and sangria,” Ms. Britt said. “We could not shut up talking to each other. I’m never letting her go as a friend.”