Truecaller is developed by True Software Scandinavia AB, a privately held company with a head office in Stockholm, Sweden founded by Alan Mamedi and Nami Zarringhalam in 2009, but most of its employees are in India.
Truecaller is a smartphone application that has features of caller-identification, call-blocking, flash-messaging, call-recording (on Android up to version 8), Chat & Voice by using the internet. It requires users to provide a standard cellular mobile number for registering with the service. The app is available for Android and iOS.
Truecaller identifies unknown calls with the most powerful Caller ID in the United States. Stay protected from spam and scams - Truecaller’s Caller ID will identify and block robocallers, fraudsters, telemarketers and other unwanted phone numbers.
The advanced spam detector will automatically block and protect you from fraudulent calls and SMS, and is updated in real time by millions of users worldwide.
According to play.google.com & wikipedia