Oct. 21 (Bloomberg) -- Twitter Inc., the short-message social-networking service, spends 97 percent of its time improving the product, rather than finding ways to make money, Chief Executive Officer Evan Williams said.

“The irresponsible thing to do would be to take our eye off that and focus on revenue,” he said yesterday at the Web 2.0 conference in San Francisco. “It’s not like we’re spending our days looking in the couch cushions for a revenue model.”

Twitter attracted about $100 million in venture capital funding last month, valuing the company at $1 billion, according to a person familiar with the matter. The company is considering generating revenue by having advertisements on the site and giving marketers deeper access to its data, Williams said yesterday.

Twitter, which lets people share 140-character messages, has yet to convert its popularity into significant revenue. The San Francisco-based company had 20.9 million users in September, up about 18-fold from a year earlier, according to ComScore Inc. in Reston, Virginia.

The growth of Twitter’s U.S. Web users has slowed, Williams said. The company is picking up the slack among mobile users and overseas customers, especially in India, Japan, Indonesia and Brazil, he said.

Companies also are using Twitter to interact with customers and distribute financial information.

“There’s a lot of commercial activity on Twitter today,” Williams said. “If we’re driving a lot of value for businesses, I’m not too worried about extracting some of that value for ourselves.”

Williams, 37, also said he doesn’t regret turning down an offer by Facebook Inc. to buy the company last year.

“Ultimately I didn’t see a reason to sell,” he said. “That’s not the point. The point is to see what we can build. It doesn’t get more interesting by being part of a bigger company.”

To contact the reporter on this story: Joseph Galante in San Francisco at jgalante3@bloomberg.net

Last Updated: October 21, 2009 00:01 EDT