Truecaller - Find a person by a name or phone number worldwide for free using Truecaller.
Google Contacts - Google Contacts is Google's contact management tool that is available in its free email service Gmail, as a standalone service, and as a part of Google's business-oriented suite of web apps Google Apps.
PhoneGenerator.net - Generate random phone numbers for all countries using the mobile phone generator. These numbers are fake, but they are built using the validations of telephone numbers.
Open Contacts - Open Contacts is an advanced address book program for managing contact info of individuals and...
CallerSmart - CallerSmart is an application that is basically used for the purpose of looking up mystery phone numbers for free.
FullContact Card Reader - Automagically scan biz cards into LinkedIn/Gmail contacts