Truecaller - Find a person by a name or phone number worldwide for free using Truecaller.
Numverify - Global phone number validation and lookup API
CallerSmart - CallerSmart is an application that is basically used for the purpose of looking up mystery phone numbers for free.
Antideo - Email, IP address and phone number validation API service
WhosCall - WhosCall is a reliable caller ID app whose popularity has led to its adoption by many users including international media. You can now manage the numbers calling you regardless of whether they are part of your contact list or not... read more.
RealValidito - Phone Validator | Free Phone Number Validation & Phone Number Lookup Service | Realvalidito