When it comes to online p2p marketplaces, Seattle-based Rover.com‘s version might be called a “pet-to-person” network.

Rover matches over 40,000 pet sitters and boarders with 100,000 pet owners in all the major metropolitan areas of the country, including San Francisco.

Most of the pets taken care of are dogs, but there are some cat sitters as well, and even a case where someone took care of a pot-bellied pig.

The service does not really compete with kennels, the traditional option for pet-owners when they need a place to board their pet, says CEO Aaron Easterly. Instead, it taps into an element of the sharing economy that already exists in the offline world.

“It turns out that ninety percent of dog owners do not engage with the existing professional market of dog sitters and kennels,” he explains. “They turn to friends and neighbors. So the solution for them has already been the sharing economy.”

On Rover.com, once you sign up you can search online for potential sitters by proximity, price point, qualifications, ratings and reviews.

“The first time you visit we recommend you message a few sitters,” says Easterly. “It’s important to find the right fit.”

Ninety percent of the time, the pet, pet owner and sitter arrange a “meet and greet,” usually at the sitter’s home, before booking a deal.

Since Rover does not require any deposit or commitment to book the work through its platform up to this point, it would be possible for the parties to make a separate deal and cut Rover out of it. But in practice this rarely happens, says Easterly, because the platform offers a rich set of benefits to those who opt into using its services.

Besides 24/7 customer support, which is free, there is also a 24/7 vet consultation service, which the owner can add on for a small fee. This way, if a dog gets sick or starts behaving oddly in the middle of the night, a vet is always on call.

Sitters can (and usually do) upload photos of the pet during its stay, sharing them with the owner via email or Rover’s free iPhone app.

A very popular feature among those sharing photos comes at the end of the visit, when Rover’s technology automatically converts the photo stream into a music video called Rover Reel.

All of this is free for the owner. Rover charges a flat fifteen percent platform fee to the sitter (dog walking is also available through the site).

As with all online p2p marketplaces, the role of ratings and reviews is the key to which sitters are the most successful.

“The first thing is that not everyone gets to be an approved sitter for us,” explains Easterly. “Less than ten percent of applicants get approved. It’s both an algorithmic and a manual process to check them. Trust is so important because pets are a part of the family.”

Once a sitter is approved and starts booking work through Rover, the company monitors the reviews and ratings and metrics like repeat bookings to determine how prominently they will be displayed on the site.

“We focus on their behavioral data,” says Easterly. “If their norms are significantly below our standards, we’ll remove them from the community.”

Like many sites that rely on ratings, Rover was initially disappointed at the relatively low number of people who chose to do so. But by actively prompting owners to rate sitters, the service has gotten the total up to 75 percent who give ratings, the overwhelming majority of which (94.3 percent, to be precise) award the top rating of five stars to their sitters.

Easterly says that repeat usage has gone up every month over the past year that the service has been open to the public, and he partly interprets this data as evidence that Rover is opening up new opportunities for people to go out of town on weekend getaways, secure that their pet is being well cared for in their absence.

There also is no evidence, he says, that Rover competes with the kennel option. “We find if our members can’t get a sitter, they revert to asking neighbors and friends, rather than go to kennels.”