Local Somerville resident Nate Barr of Zootility Tools invents the "PocketMonkey"

Some people have monkeys on their backs. Zootility Tools founder Nate Barr wants consumers to have monkeys in their wallets.

In fact, Barr has already sold 5,000 “PocketMonkeys” worldwide to date. The stainless steel tool, which is the same size and thickness as a credit card, serves 12 functions in one, including bottle and letter opener, ruler, screwdriver and banana nicker.

A successful Kickstarter campaign netted Barr’s creation more than $27,500, at least six times what he initially asked for. Now, the 31-year-old Somerville resident is thinking mass production, having placed an order for another 5,000 PocketMonkeys with a California manufacturer to keep up with growing demand.

“I’ve never had an idea take off so well, so I’ve been surprised in that regard,” Barr told the Herald. “We’ve been selling it faster than we can make it.”

Barr, a former mechanical engineer and part-time user interface engineer at Jumptap, hit upon his concept after locking himself out of his apartment twice.

“It’s always with you. You never have to think about it,” Barr said. “The real catch is it’s technically difficult to engineer something as thin as a credit card but strong enough to do the functions you want it to do.”

PocketMonkey, which sells for $12, is also compliant with Transportation Safety Administration rules, Barr said.

“I wasn’t trying to develop something to be used in a bar fight,” he said. “I think by meeting TSA guidelines you develop a pretty innocuous product.”

PocketMonkeys can be purchased online, but Barr said his goal is to market the tool to more retailers nationwide, including big-box stores that can “place orders for 100,000 of these at a time.” PocketMonkeys are currently sold in stores as varied as Davis Squared in Somerville and San Francisco’s Museum of Modern Art gift shop, Barr said.

“It’d be awesome to have it make enough money to sustain a lifestyle of trying new ideas, but even if it just lets us learn how to do this stuff, then the next idea can be even more powerful and happen even more quickly and be more efficient,” he added.

Barr is also at work on another TSA-compliant tool called KnifeNinja, which will get its own Kickstarter campaign in the near future.

As Zootility tries to keep up with orders, Barr said he is seeking another manufacturer that can produce thousands of PocketMonkeys at a time.

“What’s compelling is how many things are packed into such a small package,” he said. “We differentiate ourselves on the personality of our tools, that people see it as a premium brand over perhaps some cheap knockoffs. Other people try to imitate the intention, but not the execution.”