Concern about privacy, and frustration over censorship and content blocking is driving millions to use anonymity tools

The gathering crisis of trust around consumer web services and the fallout from Edward Snowden's revelations is fuelling a significant uptake in anonymity tools, new research shows, as internet users battle censorship and assert their right to privacy online.

Globally, 56% of those surveyed by GlobalWebIndex reported that they felt the internet is eroding their personal privacy, with an estimated 415 million people or 28% of the online population using tools to disguise their identity or location.

Aggregating market research data from 170,000 internet users worldwide, GWI found that 11% of all users claim to use Tor, the most high profile for anonymising internet access.

On these figures, Tor could be regularly used by as many as 45.13 million people. Its biggest userbase appears to be in Indonesia, where 21% of respondents said they used the tool, followed by 18% in Vietnam and 15% in India.

Indonesia also has the world's highest penetration of general anonymity tools among its internet users, with 42% using proxy servers or virtual private networks known as VPNs, which disguise the location of the user's internet connection - their IP address - and therefore bypass regional blocks on certain content.

34% of Chinese using anonymity tools

The Chinese government reportedly employs as many as 2 million "internet analysts" to review and block content deemed politically or commercially inappropriate, yet GWI research estimates that 34% of the country's online population disguise their online location so that they can bypass such filters.

Of those that use VPN or proxies, 60% say they do so to access Google's YouTube video site, and 55% said they use it to access Facebook and Twitter.

The use of IP-masking tools means that size of China's Facebook and Twitter userbase, for example, could be significantly larger than first thought. China's VPN-using audience alone could be as much as 160 million people, many of whom are currently being incorrectly identified as being in another country - usually the US.

Normally, the location of a user's IP address would be used to deliver relevant regional advertising as well as a version of the site in the local language.

Geo-located advertising 'missing the mark'

"VPNs serve a perfect dual purpose for consumers in lots of markets, allowing them to access restricted content and better content as well as stay anonymous," said Jason Mander, GWI's head of trends. "It's a perfect combination and one that is likely to see their popularity grow. It also means that the numbers using sites such as Facebook in China are likely to have been under-estimated, and that geo-located advertising is completely missing the mark for these internet users."

"The figures also suggest that the global internet audience is a lot savvier and more concerned about this type of thing than is traditionally supposed, and chimes with the statistic that 55% are concerned about their privacy being eroded by the internet."

In Vietnam, VPN is used by 38% of the online population and in Brazil and Thailand 36%. Mexico, India and China all reported use by an estimated 34% of the population that has access to the internet, with the UAE and Argentina on 32%.

The US, UK, Germany and Ireland meanwhile all report 17% penetration, with Japan the lowest at 5%. The data includes those aged 16-64 for the last quarter of 2013.

The data also underscores the shift from text messaging to mobile messaging apps, with WeChat seeing a 379% increase in active users between the second and fourth quarters of 2013 to around 385 million users, 78m of whom are in China.

Instagram beats Facebook for growth, and younger users

Facebook has by far the biggest audience among social networks with an estimated 1.1 billion active users, but also has a very active user base with 56% saying they visit the site at least once a day.

Facebook's $1bn acquisition of the photo-sharing site Instagram in 2012 proved a sound bet; GWI found it had the fastest growth of any social platform in 2013 adding 23% active users from Q2 to Q4 to reach 91 million users. Instagram also led the move of younger web users away from more established social sites.

Along with Twitter, Facebook has the largest proportion of users aged 55-64, while Tumblr and Instagram have the highest share of 16-24 year olds at 45% and 39% respectively. Use by older people is compounded by the ageing of early-adopter users as well as older users being more likely to join established sites.

The most common activity on Facebook was sharing content, private messaging and commenting on posts, while the least popular activity - which doesn't bode well for the site's advertising strategy - included complaining or commenting on a brand or sharing brand videos.

MySpace, meanwhile, languishes at the bottom of the charts. Despite an ambitious and sophisticated redesign, the site has not integrated sharing with other networks and has struggled to regain its former glory. According to GWI it has the lowest numbers of active monthly accounts, has seen the biggest drop in user numbers for 2013 and fewer daily visits.

• A beginners guide to Tor