Truecaller is a mobile application that helps users identify and block incoming unwanted calls, spam, and telemarketing calls. It was developed by True Software Scandinavia AB, a Swedish company founded in 2009. The app uses a large database of phone numbers and caller profiles to identify incoming calls from unknown numbers, even if the number is not saved in the user's contact list. The app also allows users to search for phone numbers, call history, and messaging history. Additionally, Truecaller offers features such as call recording, voice messaging, and SMS filtering.