"We have a lot to concern ourselves with, just building Twitter," Dorsey said when asked at a technology conference whether he was worried that Google's own fledgling social network would come after Twitter.

"Social is just one part of what we do. We think of it as an information utility," he said, describing Twitter as a personal news service as much as a social network.

"You don't have to tweet at all," he told the DLD conference in the German city of Munich. "The biggest value is finding out what's happening in your world in real time."

Twitter, which lets people send 140-character messages, or tweets, to groups of followers, has more than 100 million active users.

Investors are eagerly awaiting a market float that could value the company at around $8 billion.

Skeptics contend that the site has not yet proved it can make money. But Dorsey, who is the company's executive chairman, said advertisers were proving willing to pay to promote their tweets, accounts and trends.

"Our business model has been in development for quite some time, and it works," he said.

Twitter is expected to have made about $140 million in revenue last year, according to an estimate by industry research firm eMarketer.

Dorsey said Twitter was building a team in Germany, where privacy concerns run high and engagement with Twitter has been relatively low.

He added that the company was always open to making acquisitions to acquire the talent it wanted.

Dorsey is also the founder and chief executive of fast-growing mobile payments start-up Square, which he said he wanted to expand internationally this year.

"We would love to come to Europe, and we're going to work very, very hard this year to bring it outside the United States," he said. "We're looking at China. We're looking all over Asia."

(Reporting by Georgina Prodhan; Editing by Jan Paschal)

• A Permanent Economic Emergency