Editor's note: Twice is one of Inc.'s 2015 30 Under 30. This year's readers' choice winner is ThinkLite.  

Both founders of secondhand retailer Twice bring plenty of experience in buying and selling used clothing to their venture. Noah Ready-Campbell, who grew up in a small mountain town in Vermont, and Calvin Young, a Chinese immigrant whose family settled in the Virginia when he was 2 years old, both landed scholarship admission to boarding school (Philips Exeter and North Carolina School of Science and Mathematics, respectively). But the only way they could afford to comply with their school dress codes was to shop at secondhand shops. Noah Ready-Campbell was a Salvation Army aficionado and Young was a Goodwill regular.

"I remember I really liked Brooks Brothers shirts," says Ready-Campbell, Twice's CEO. "I got one that had a $250 price tag on it for $10."

These early experiences, and their challenges with selling their used goods online, were the inspirations for Twice. "Noah and I were used to buying and selling things on eBay," says Young. Their biggest pains were taking photos of items, answering  a bunch of questions from the buyer, and shipping the goods. So, Young adds, Twice seeks to "abstract away all of that pain."

Easing the way for sellers

The company allows sellers to ship a box full of laundered used clothes to Twice, which gives the seller a single, all-or-nothing offer for the items that were sent. If the offer is accepted (as it is in 97 percent of cases), Twice uses a proprietary software program called Vulcan, designed by Young, to take photos of the items, color correct the images, determine suitable prices, and upload the photos and descriptions to the Twice website. Vulcan also helps manages inventory and personnel, such as hours and shift assignments, at its 25,000-square-foot warehouse in San Francisco.

When Ready-Campbell and Young and first got their idea, they wanted to determine if sellers would trust them enough to send their clothes with just the promise of possible payment. So they launched a rudimentary website, and when boxes of clothes started arriving, they knew they were onto something. They used investor funds to buy 1,000 pieces of clothing at Goodwill to prime the site, and the inventory sold down faster than they predicted. Today, the company buys items directly from sellers and the products are stored in the company's warehouse and then shipped to buyers for just $4.95 per order, or free for orders over $49.

Currently, the site sells women's and men's clothing, shoes, and handbags. Approximately one-third to one-half of the product they receive is unsellable, so Twice sells those items to a recycling company or to brokers who ship it to developing countries. The long-term vision for Twice is to expand to all types of clothing, jewelry, and accessories and eventually sell "basically anything that's under your roof, in your closet, in your garage, cluttering up your space," says Ready-Campbell.

"No chaos"

The company has already raised $23.1 million from investors, the largest being Andreessen Horowitz. Jack Abraham, a Twice investor, serial entrepreneur, and former classmate of Ready-Campbell's, had also invested in the pair's first business idea, a micropayment company. This wasn't because he thought the company had legs (he didn't), but because "Noah and Calvin are great minds. They learn things very quickly and they don't have an ego about their ideas," says Abraham, also an Inc. 30 Under 30 alum.  When they pivoted to Twice, Abraham invested even more money. And although the founders won't disclose revenue figures publicly, the company has 48 full-time employees, over 230 part-timers, and plans to expand to an even bigger warehouse soon.

The key to their growth, says Ready-Campbell, is two-fold. Twice has made it easy to sell used goods and it strictly adheres to its business mantra, No chaos. That flies against the "move fast and break things" ethos of Silicon Valley, but it makes sense for their business, says Ready-Campbell. "When you are working with engineers and writing code, you can move fast and break things and you probably should because it lets you iterate more quickly. But when you're talking about 250 hourly folks who all need to be trained and retrained any time you change anything, who all need to be on the same page, you have to run things a lot differently."