Jennifer Moss is not your typical Reddit user. Every week, the 33-year-old utility company analyst from Marietta, Ga., reads posts on the social news site Reddit to see if she can help people who say they are in need. A father says he can’t afford to take his son on a trip? She sends him gas money via Paypal. A pregnant mom says she ran out of food stamps to buy vegetables? She sends her a gift card to a produce company. “Just because I never met them, doesn’t make them any less in need,” Moss said.

Last month, nearly 170 million visitors flocked to the site, which currently boasts more than 9,600 active communities that are typically devoted to niche subjects, anything from diet and exercise to video games. And while the site has occasionally drawn attention for the wrong reasons — a spokesperson apologized in 2013 for users who falsely accused a student of plotting the Boston Marathon bombing — its most fervent participants celebrate Reddit for fostering a vibrant community.

On May 28, 2014, Kayla Davis of Columbia, S.C., posted a message on the site about her need for a kidney transplant. Since age 10, Davis had suffered from a kidney disease called glomerulonephritis, which damages the parts of the organs that filter waste and fluids from the blood. She had been on dialysis for the last three years, which always left her feeling exhausted. Playing video games like The Legend of Zelda was the only thing Davis said she could do that wouldn’t wipe her out.

Davis was looking for a live donor with an O blood type. After setting up an unsuccessful Facebook page and realizing her mom and brother weren’t good matches because they have thyroid problems and high blood pressure, respectively, Davis, a 26-year-old, turned to Reddit. “It was almost like a last resort,” she said.

Five hours after the plea was posted, Moss posted a note of her own, saying she would call a living donor coordinator the next day and start the necessary tests to see if she was a match. They were. And Moss decided to donate her kidney. “I have something that the other person needs, and if it’s not going to hurt me, why not?” she thought.

Over the next nine months, the pair exchanged messages on Facebook three to four times times a week and found out they had more in common than a blood type. They both loved pizza, which Davis couldn’t eat when she was on dialysis. They also loved dogs, especially corgis. Moss regularly sent Davis photos of her corgi-Jack Russell terrier mix Conan, named after comedian Conan O’Brien, to keep Davis’s spirits up.

They met for the first time in March before the transplant surgery at Georgia Regents Medical Center in Augusta. The surgery took place on March 26. It was a success: both women were up and walking the next day. Worried that Davis would be bored or lonely when Moss was discharged first, she and her fiancé Chris Telford bought the younger woman a tablet computer so she could keep up with friends back home.

The pair are not the first organ donor and recipient to meet through social media. Last year, a 36-year-old man found a live kidney donor on the social network, and a Minnesota mother found one for her two-year-old daughter after making a Facebook page. Over the past month, Sammy Griner, an 8-year-old boy known from the Internet’s popular “Success Kid” meme, raised more than $100,000 for his dad’s kidney transplant surgery through crowdfunding. And in March, a photo of an ad on the back of a man’s pickup truck pleading for a live kidney donor for his wife went viral on Reddit, flooding the University of Colorado hospital’s voicemail with calls from potential matches.

Moss hopes the chance way she met Davis can set an example. As of April, more than 101,000 Americans were waiting for a kidney, according to the Organ Procurement and Transplantation Network. “If someone can see how easy it was for me to go through this process,” Moss said, “they might look at themselves and go, ‘Well, I could do it.’”

Finally off dialysis, Davis says she wakes up before 6 each morning filled with energy. She plans on getting a driver’s license. She wants to apply to college and pursue a career in computer science. Davis continues to share her story on Reddit, posting reguarly to let fellow users know about her recovery. And in September, Davis will see Moss again. This time, they’ll meet at Moss’s wedding.

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Write to Olivia B. Waxman at olivia.waxman@time.com.