Over 50 million users: Kik, the free messaging app which is causing worries for parents. Photo: Supplied
Police have described it as ''the No.1 social media problem involving teenagers'', but most parents would barely have heard of messaging app Kik before last week.
Kik is a free texting app used by more than 50 million people and enables users to connect with strangers. Although it is for people aged 17 and older, experts say children aged 11-15 are the main users.
The app can be installed on iPod Touch and iPad devices as well as smartphones. Instead of using phone numbers or real names to contact each other, each Kik member has a user name. Conversations and images cannot be viewed publicly, which makes it much harder for parents to monitor Kik than Facebook or Twitter.
Cyber safety expert Ross Bark said Kik and Instagram were a ''dangerous combination'' for teenagers, who posted photographs publicly on Instagram and then invited viewers to ''Kik me'' privately to chat.
''They're literally promoting themselves, saying, 'Come and talk to me,''' he said. ''They can randomly chat with somebody and send images, and they don't understand the consequences of who is using that information.''
NSW Police Force social media spokesman Strath Gordon said police were concerned that drug dealers and paedophiles trawled Kik, ''taking advantage of that hidden communication'' to target young people.
''It's hidden to most parents,'' Mr Gordon said. ''Young people may not even know who they are communicating with. No one is using their real names and that's a problem … social media is very agile. Criminals move from platform to platform where they feel their chances of being detected can be reduced.''
Kik has also become popular for sexting strangers.
But experts say blocking Kik or banning children from using the app is not the answer. Instead, they advise parents to educate themselves about the social media their children are using, and to set boundaries for that use.
Kik did not respond to Fairfax Media questions.