Inc.'s 11th annual 30 Under 30 list features the young founders taking on some of the world's biggest challenges. Here, meet Bark & Co.

There's Dollar Shave Club for guys, Birchbox for gals, Blue Apron for gourmets, and NatureBox for snackers--so why shouldn't Spot and Buddy have their own subscription boxes as well?

Thanks to Matt Meeker, Carly Strife, and Henrik Werdelin, the canine-crazed co-founders of Bark & Co., dogs can now start looking forward to the mailman's arrival. BarkBox provides a monthly delivery of innovative treats and toys that pups can wolf down and tear apart to their hearts' content. The growing number of consumers eager to pamper their pooches has fueled some impressive growth: the five-year-old company has shipped more than 20 million products. While the company has competition, such as PetGiftBox and Pawpack, it's still the biggest player in the space, says Strife. In fact, the company just announced $60 million in Series C funding led by August Capital. Bark & Co. doubled revenue last year and is on track to do the same in 2016.

Meeker and Werdelin, who were randomly paired as roommates at a Summit Series event, met Strife through a friend in 2011. At the time, she was part of Uber's launch team. "We realized we were all dog-obsessed people, and wanted to do something in that space," says Strife. "We saw the traction that Birchbox was getting, talked to the founders for advice, and learned a lot about their business model."

Financed by friends and family, they shipped 94 boxes to folks they signed up by pitching friends and acquaintances. "We went around with a PDF and a Square," Strife recalls. In April, during their first year in business, they found that Meeker's dad (who has a dog, but is far from internet-savvy) had signed up for a subscription. "He didn't even know yet that [Meeker] was involved," recalls Strife. It was the first sign that they were onto something big.

Initially, the founders scoured Etsy and a variety of trade shows to unearth products that pet owners wouldn't typically find at, say, Petco. Now, the company partners with its vendors to develop new products. Will Chen, co-founder of San Francisco-based P.L.A.Y., says that Bark helped his company, a maker of premium pet bedding, branch out into pet toys. The two companies brainstorm ideas, and P.L.A.Y. produces the product which is first launched exclusively in BarkBox subscriptions, then makes its way onto P.L.A.Y.'s website. "We grew more than 50 percent last year and I would say that BarkBox contributed 60 to 70 percent of that growth," says Chen.

Bark & Co. is mum about its subscriber numbers, but Strife says the company has shipped a total of over four million boxes. The company has also branched out to include several other businesses. Its advertiser-supported BarkPost is filled with dog news and videos and gets 10 million unique visitors a month; BarkShop is an e-commerce site where customers can buy all manner of dog paraphernalia without the committing to a subscription; and BarkLive sponsors dog-centric live events such as Open Bark Night, where waggish stand-up comedians share drinks and dog stories ("Three corgis walk into a bar ... ").

Strife says the company also has donated more than $1 million in cash, adoption support, and volunteer time to more than 3,000 dog-related charities, including shelters and rescue organizations. And then there's BarkGive, a crowdsourcing platform for dog-related causes.

BarkBox still accounts for the lion's share of the company's revenue (75-80 percent), says Strife. Still, she notes that the company is constantly evaluating new business models, with a goal to launch one or two new businesses each year. Werdelin is also a co-founder of Prehype, an innovation and product-design studio that incubated Bark & Co. "We share an office with Prehype," says Strife. "Innovation is definitely at our core."

But innovation within Bark & Co. hasn't always been a runaway success. In February 2014, BarkCare, an in-home veterinary care division that launched as an "Uber for vets," went to the happy hunting grounds after a fitful year. "We partnered with vets and had two staff vets in New York and San Francisco," says Strife. "But we realized we're not vets, and we don't know how to be innovative in that space."

On deck for this year: Taking the knowledge garnered from selling more than 20 million products and using it to develop a Bark & Co.-branded line of toys and treats. As for other animals--such as, gulp, cats--Strife concedes her team has been somewhat mystified by the relationship people have with them. "We would sooner go into the baby space than that of any other animal," she says.