When David Adams moved back to Seattle, he settled in an apartment on the seventh floor of a building in the city’s Belltown neighborhood. On Tuesday, Adams and his dog Soba were enjoying a grassy backyard behind a stranger’s house in Ballard, thanks to the company Adams started six months ago.

SniffSpot is a marketplace that connects dog owners, who are looking for a safe and convenient space for their pet to get some exercise, with property owners, who have room outside for pups to play — and the desire to make a little easy money on the side courtesy of the sharing economy.

Originally from Ohio, Adams, 31, moved to Seattle in 2010 and spent just over three years at Microsoft. He moved to San Francisco to found his first company: 2nd Address, a marketplace that helps users find monthly furnished housing. That company raised more than $12 million in funding, and Adams still maintains a seat on the board and travels to San Francisco regularly.

“The trend that I have is that when I start a company, I start it based on my own problem,” Adams said. He used to always live in furnished rentals, until his girlfriend expressed an interest in something different. “I adopted Soba a year and a half ago and I’ve been taking her around to dog parks. She’s super high energy. I just always have had bad experiences there.”

Integrating pet services and technology is part of a growing trend that appeals to people in larger cities, especially in places like Seattle where so many Amazon employees and others take their dogs to work. Seattle-based Rover has found huge success with its pet-sitting and dog-walking marketplace, and SniffSpot is clearly playing off that demand — with a twist of its own.

“Thirty percent of dogs are owned by millennials, and millennials are moving into cities,” Adams said. “So you’re having an all new set of problems with dogs. That’s why you’ve seen Rover be so successful, you’ve seen Wag be so successful, because they’re new services that appeal to urban dog owners. It’s just getting started.”

Seattle Parks and Recreation offers 14 off-leash areas for dogs to run free. But after Soba was bit at a dog park and required a vet visit, Adams figured there had to be a better way to get his dog the fresh air and exercise she needed.

“I think that dog parks are a really important public service. You’ve got to have them in the city,” Adams said. But SniffSpot caters to people and pets who are looking for a more controlled environment, often because the animal comes from a background that makes it more reactive around other dogs and people.

SniffSpot works pretty much like Airbnb, the online hospitality business. Through its website, SniffSpot users can browse a variety of host properties — there are about 70 in the Seattle area right now and Adams is hoping for many more. Hosts provide information and pictures related to the property, including details about fencing. They can set restrictions on times, breeds and numbers of dogs allowed at any given time. It’s possible to reserve a space for solo dog time, or meet up with others. Users choose a date and time to reserve and pay through the site.

In Ballard, I met Adams and Soba at a typical house in the neighborhood, advertised on SniffSpot as “Fully Fenced Whittier Heights Yard.” We let ourselves in through the side gate and found a sizable area in the back for Soba to explore. There were toys scattered about and a bowl full of water on the back deck.

“Having off-leash exercise is really important for a dog’s health,” Adams said, as he talked about the full range of exercise that a dog requires, beyond walks on a leash, and how that benefits the animal not just physically, but mentally, too. It’s clear that the young entrepreneur is combining his marketplace and tech experience with a new passion for pets.

“I’ll be the first to say I didn’t know anything about dogs when I adopted Soba,” Adams said. “And I’ve been learning a ton.”

A totally bootstrapped endeavor, SniffSpot is pretty much a one-person operation right now. Adams has relied on contractors for a little bit of help, but he’s taken no outside funding and is doing no marketing right now. He believes the right way to start a company is to build a product that people want and need, and then the product will take off on its own. In the two full months since the website has been up and functional, SniffSpot has seen 60 percent growth month over month. An app will get built eventually, he said.

There’s no requirement to be a host on SniffSpot, so long as the property doesn’t contain any hazards and is owned by the person posting it. Hosts are vetted through name, email and address checks and generally there is an interview and even a site visit if needed. Hosts can set their own price, with $4 being the minimum per pet, per hour. SniffSpot takes 12 percent of the revenue.

“We’ve got hosts on our platform making $60 a day,” Adams said. “You’re not investing in the space. You’re not working. It’s not like Uber where you’re going and driving for hours to make money. You just let someone come use your yard — maybe you’re at work or something else and you’re just making incremental income.”

Users are expected to treat the space like it’s their own — clean up the dog poop and toys, be courteous to neighbors, etc.

SniffSpot hasn’t officially launched outside of the Seattle area yet, even though some properties are listed around Washington and in other states. A couple listings on the site show the possibilities beyond a backyard romp.

Just past Monroe, Wash., a 175-acre farm includes a wooded area and access to the Skykomish River for $10 an hour. And south of Seattle in Cinebar, Wash., 40 acres of dormant timber land on a mountainside are available. For anyone who is apprehensive about hiking in open areas with their dog off leash, the bigger SniffSpot properties could provide a solution.

Adams, who goes to SniffSpots pretty much every day, sometimes multiple times a day, said there are a million examples of people sharing things these days, but that SniffSpot doesn’t really compare. It’s not really invasive because no one enters your house, they’re in a controlled space, they stay for an hour and leave.

Sitting behind someone’s house in Ballard, in rapidly growing and housing-crunched Seattle, he admitted how special a place it was.

“If everyone had their own yard, there’d be much less demand for something like SniffSpot,” Adams said. “It’s amazing that these yards actually even exist still.”