The online craft bazaar Etsy made its debut on the Nasdaq stock market Thursday, signaling the birth of an unusual public corporation — and not just because its employees carry around compost on bicycles, or because its regulatory filings are peppered with phrases like, “We keep it real, always.”

Etsy is one of a growing number of companies, called B Corps, that pledge to adhere to social and environmental accountability guidelines set by a nonprofit organization called B Lab. And Etsy on Thursday became only the second for-profit company to go public out of more than 1,000 companies that have that certification.

Etsy shares closed on Thursday at $30, almost twice their initial public offering price, in one of the most closely watched market debuts this year.

Ringing the opening bell at Nasdaq’s headquarters in Times Square, amid cheers and confetti and Etsy ads flashing on the screens outside, Etsy’s chief executive, Chad Dickerson, called the debut “an important milestone.” Selected Etsy vendors held a bazaar of their wares in one corner of the square, including a Brooklyn-based vintage clothes seller, an Israeli jewelry designer and a Somerset, Mass., store that sells superhero capes for children.