The Truecaller app which helps people identify calls from unknown numbers, is not safe as it captures metadata of incoming and outgoing calls and messages. The app can lead to identity theft as it shares the information that you may not want to be shared. The installation and use of the policy of the app, developed by a Swedish firm, states that it gathers data which includes the content you view, search terms, websites and everything about your phone. If you install the app you are giving away your relatives, friends and colleagues information without even asking them.
— source deccanchronicle.com