An Instagram post lead one woman to rescue a dog left abandoned in the New York City subway in Manhattan.

How much is that doggie in the window? If it’s too expensive, maybe check social media for a free one.

On Facebook, they are often known as “Buy Nothing” groups. On Instagram, there is an account many follow called “NYC Free at the Curb.” The accounts may have different names, but their purpose is the same.

They are virtual communities where people can share their unwanted belongings in hopes that another user will find a use for them.

Usually, these sites are home to used chairs, old TVs, already-read books, but on Monday one woman found an unlikely friend on the NYC Free at the Curb Instagram page.

“I found my coffee table; I found my couch that I was sitting on when I saw this dog. I found so much on this page, so this is my craziest stoop find yet,” Heather Hamm said.

Hamm had been thinking of getting a dog for some time. After another woman sent in a photo of a confused and sad-looking pit bull mix, tied with a rope in a subway station… Hamm could not resist.

She hopped in a Lyft to the Fulton Street Station, where she saw some police officers standing with the dog.

“I was just like, ‘Can I have her?’ And they were like, ‘She’s your dog now, she obviously likes you,'” Hamm said.

And it did not take long for Hamm to come up with her newfound pup’s name.

“I called her Peaches, and she responded. So, I kind of think that’s already her name,” she said.

The identity of whoever abandoned Peaches in the subway is a mystery.

While there are plenty of cameras above ground in the Financial District and down in subway station, there are none in the stairwell where she was found.

Hamm took her to the vet, who did not find a microchip, and estimated that Peaches was between six and nine months old

Less than 24 hours after her photo was posted on Instagram, Peaches has a clean bill of health from the vet, a new pink harness and a new parent.

“I opened up Instagram and I saw her. She was the first post on there. And I was like, there she is,” Hamm said.