Truecaller - Find a person by a name or phone number worldwide for free using Truecaller.
CallApp - Free Caller ID & Call Blocker app that allows mobile users to block phone calls, identify calls, blacklist unwanted callers and much more.
Sync.ME - Search over 1 Billion phone numbers worldwide. Identify unknown phone numbers and block unwanted calls.
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ThisNumber - ThisNumber helps you find phone numbers for people and businesses!
Hiya - Know who's calling or texting and block spammers on Android