Twitter has seen a fresh growth spurt over the past six months, particularly from those using smartphones, even as the company struggles to find a way to make money from its influx of users.
Both the number of users and their tweets of 140-character updates has been rising sharply, driven by news such as Osama bin Laden’s death, big events including the Uefa Champions’ League football final and general interest in celebrities, such as pop star Justin Bieber.
A survey released on Wednesday by Pew Research Centre found that twice as many American internet users aged 25 to 44 were on the service in May compared with six months earlier, with 13 per cent of connected US adults now on Twitter versus 8 per cent in November.
However, Dick Costolo, Twitter’s chief executive, said that those figures were vastly understated, adding that third parties have not been able to measure the total usage because of the variety of software interfaces and devices employed to communicate through Twitter.
“What we see internally is that we are growing much faster than that,” Mr Costolo said at a Dow Jones technology conference outside Los Angeles. “We have grown our mobile usage over 150 per cent since the beginning of the year.”
Pew found that half of US Twitter users access the service from a mobile device.
While Mr Costolo declined to say whether Twitter was profitable or when it might seek a public stock sale, he announced improvements to the site’s functions at the conference and said the introduction of advertising last year had already produced “unbelievable” results for marketing campaigns.
Mr Costolo said Twitter would in the next few weeks roll out new functions that made sharing photos and videos nearly as easy as sending the 140-character texts and shortened web links that are the most common use of the service.
The topic search function will change to rank tweets, as the messages are known, by relevance instead of in reverse chronological order. The results will be ordered based on factors such as the authority of the sender and how many followers he or she has and will also include the most popular photos and videos associated with the topic.
“We are surfacing all of the context around the tweets now,” Mr Costolo said.
The number of advertisers on the site has grown from 150 at the end of last year to more than 600, with rates of engagement approaching those for Google’s Adsense. A sponsored “trending topic” from Volkswagen led 52 per cent of those who saw it to click through, comment or retweet it, he said.
Although Pew records internet users’ perceptions of their own behaviour, the indication of a fresh acceleration in Twitter’s growth was echoed by research house ComScore, which estimated a 47 per cent increase in unique visitors to Twitter’s website in the year to April, to 123m people globally.
Mr Costolo cited a far higher internal figure, some 350m unique users per month.
Analysts believe that 300m people have signed up to use Twitter since its creation in 2006, although the company will confirm only that it has “more than 200m registered accounts”.
Aaron Smith, analyst at Pew, said: “It is a tool that has a low barrier to entry – it’s amenable to using on your mobile device and it doesn’t require you to register if you want to dip your toe in the stream.”
The volume of information posted on the site also continues to grow, with about 1bn tweets every six days.
Last week during the Champions League soccer final between Manchester United and Barcelona, Twitter reached its second highest spike, at 6,303 tweets per second, more than double the record set during the football World Cup last summer but behind the peak of more than 7,000 during new year celebrations in Japan.
In the UK, wider public interest in Twitter has been piqued by several accounts that have broken press gagging orders brought by celebrities in an attempt to protect their private life. According to Experian Hitwise, UK traffic to Twitter hit an all-time high during last week’s “super-injunction” debate, accounting for one in every 184 visits to a website on May 21.
Additional reporting by Richard Waters in San Francisco