Twitter said Thursday that the number of active monthly users has soared to more than 100 million with the majority of people logging in on the go.

"We're seeing tremendous growth on mobile," Twitter chief executive Dick Costolo said during an informal "State of the Union" update with reporters at the microblogging service's headquarters in San Francisco.

The number of "global active users" -- people who log in at least once a month -- has jumped 82 percent from the start of the year with mobile climbing 40 percent each quarter for the past year, according to Costolo.

More than 400 million people visit the twitter.com website monthly as compared with 250 million at the start of the year, according to figures he provided from a Google analytics service.

"There are still a lot of people who don't log into Twitter but use Twitter every day," Costolo said. "They come and search or read pages."

An average of 230 million terse text messages, many of them "retweets," are fired off daily at Twitter in a 110 percent increase since the start of the year.

About 40 percent of the people considered active users of Twitter don't send messages, referred to as "tweets."

"We are excited about that," Costolo said of the growing ranks of people who peruse Twitter but don't actually tweet.

"I think that is super healthy," he continued. "Now we will see how to migrate them from this consumption experience to publishing."

Twitter has overhauled its infrastructure to handle the blistering growth and avoid frequent service disruptions that made its "fail whale" crash page infamous.

"Every time we innovated or added a new product the website had problems; the fail whale," Costolo said. "We were at capacity."

In comparison, Twitter "didn't even blink" about two weeks ago when it hit a new record high of 8,900 tweets-per-second on the wings of news that singer Beyonce is pregnant.

"Now a big thing is surfacing all the content pouring in every day," Costolo said. "We are at a billion tweets every five days and that continues to accelerate."

He dismissed the threat of competition from a freshly-launched Google+ social network.

Google+ will pull in massive numbers of users by bundling together the Internet giant's other popular offerings including search, YouTube, Gmail, and the Android software mobile platform, Costolo predicted.

"I think these other platforms will add services and capabilities and we will try to edit ours down," Costolo said. "We are thinking differently in how we can simplify the product further; what we can take out."

Twitter engineers are working to make things "dead simple" for users and consistent across the myriad devices people use to access the Internet, according to the chief executive.

Twitter had put a moratorium on new features until it beefed up its infrastructure. Twitter is poised to begin rolling out changes selectively and slowly, according to Costolo.

"We want an interface that captures the roar of the crowd as well as the volume of the conversation," he said. "That is very hard; you have to surface the signal and eliminate the noise"

The health of Twitter's business is strong and a recent infusion of $400 million has left the startup feeling no pressure to go public with a stock offering, according to Costolo.

"We have what can only be referred to as a truckload of money in the bank," he said. "We want to be able to remain independent and not beholden to public markets."

Promoted tweets that act essentially serve as paid advertising on Twitter will spread throughout the platform and the company is happy relying on them as is main revenue pump.

"We are just going to focus on scaling the advertising business," Costolo said. "We don't think there is anything we need to do to make more money."

Twitter also takes in cash by licensing access to the stream of data gushing through its network but has no plans to expand that revenue stream.