The founder and CEO of Twitter didn't need 280 characters to give a shout out to a Charleston company that's tapping into the cryptocurrency field. 

"Simple and awesome," Jack Dorsey, who's also chief executive of Square, tweeted about a security device he had just bought from Casa Inc.

Dorsey, a cryptocurrency enthusiast, broadcast his recommendation for Casa's technology March 1 from his handle "@jack," which has 4.2 million followers.

"I would have been satisfied if he was a happy customer," Casa CEO Jeremy Welch said. "We're very grateful."

Casa makes technologies that store and secure bitcoin. Bitcoin allows users to exchange money on an open, decentralized platform. Unlike brick-and-mortar banks, cryptocurrencies are not beholden to a central authority.

Soon after raising a $2.1 million investment round last year, Welch said the company's services would be tailored to investors with at least $400,000 in crypto assets. Those plans have changed somewhat. Welch now imagines that his technologies can find a place in every home. The company has begun selling its devices online.

Six months ago, Casa announced it would begin offering a physical device called a node, which allows users to manage their owns cryptocurrency networks. An hour after offering 100 of them to buyers, they sold out.

The price is $300. That includes a subscription to its lowest membership tier. Subscriptions run up to $5,000

Welch is a longtime entrepreneur and has worked in the tech industry since 2007. Casa has a presence in Charleston, though Welch said he spends most of his time traveling. The firm has about 24 employees, with a handful based locally. 

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Casa has been likened to a digital wallet before, though Welch doesn't agree with the analogy. He said the company's technologies serve more as a safe deposit box that give users a high level of control over their crypto assets. 

"Bitcoin is a revolution in giving control back to consumers," he said.

Dorsey said on a recent episode of the podcast "Tales from the Crypt" he has been fascinated with digital currency for years. He noted he exceeded Square's "Cash" app $10,000 weekly limit using bitcoin. 

In response to a question about Casa, Dorsey told the "Tales from the Crypt" interviewer he had just received his device and planned to tinker with it. 

"I love experiencing entirely new technologies that people have worked so hard to produce," Dorsey said. "I love software, but I love the tangibility of this box."

Of course, the device can be purchased with cryptocurrency. 

Reach Mary Katherine Wildeman at 843-937-5594. Follow her on Twitter @mkwildeman.