Catherine Alexandrov sorts through stock at Big Skinny’s offices in Harvard Square. The company sells wallets and other products made of nylon microfiber that mean three to five times less bulk than a traditional wallet, she said. (Photo: Marc Levy)

Catherine Alexandrov sorts through stock at Big Skinny’s offices in Harvard Square. The company sells wallets and other products made of nylon microfiber that mean three to five times less bulk than a traditional wallet, she said. (Photo: Marc Levy)

When Kiril Alexandrov’s wallet grew uncomfortably thick, as everyone’s does, he did something about it: He made a better, skinner wallet out of nylon microfiber, launched production and opened a business.

Thanks to Alexandrov, when your wallet grows uncomfortably thick and you want to do something about it, all you have to do is go to one of the small shops reselling his wares or direct to bigskinny.net.

“He just got tired of sitting on his thick wallet,” said his wife, Catherine Alexandrov, Big Skinny’s marketing director.” Apparently, every man wants a thin wallet.”

In fact, she said, a look into online shopping patterns revealed that the most popular search for a wallet isn’t just “wallet” — it’s “thin wallet,” and that leads people to Big Skinny, either on its own site or on Amazon. The company promotes its wares as being three to five times skinnier than the average wallet, sometimes less bulky loaded with cash and cards than are empty wallets made with more traditional materials.

About 75 percent of Big Skinny sales are online, boosted by a 20,000-strong e-mail list; but there are also retail stores such as Passport in Harvard Square and Davis Squared in Somerville; kiosks in such places as Jacksonville, Fla.; and about a half-dozen representatives who hawk at street fairs and specialty shows. In January the company brings on its first sales representative in Canada, although international shoppers have always been a large part of Big Skinny’s demographic. “It’s easier for them to think outside the box instead of just going for the most popular brand,” Catherine Alexandrov said.

Production is also international, meaning manufacturing is overseas, she said. The Alexandrovs explored options in the United States but realized “we’d have to charge $100 a piece if they were made here.” Instead, Big Skinny’s entire line of wallets, card cases and apparel sell for about $13 to $30.

As part of her duties, Catherine Alexandrov recently redesigned the company’s Web site and, over Thanksgiving, began its first advertising in five years of operation — posters with tear-cards on the Red Line.

The steps, along with the addition of a women’s line, brought another “exponential” leap in sales growth to a low-cost startup company described as being in the black “almost immediately.” She would not discuss figures.

The goal for next year is to expand the women’s line and introduce computer bags, which may well bring more hiring and a need for more space.

For now Big Skinny operates out of claustrophobic offices in Harvard Square, not far from the Alexandrovs’ condo, revealing one of Kiril Alexandrov’s previous gigs: running the Boston Book Review. Bookshelves holding review copies of books shrink the space within which Catherine Alexandrov and three feverish assistants race to fill orders.

He is a Bulgarian-born Harvard graduate and serial entrepreneur who has sold a biotech company and linked Russian diplomats and U.S. businesses through his International Economic Alliance.

But selling wallets hasn’t bored him.

“We’ll ride with this one for a while,” Catherine Alexandrov said.

[Full disclosure: The reporter was given a Big Skinny wallet. It works as promised, cutting significant bulk from the back pocket where a wallet is kept.]