Truecaller - Find a person by a name or phone number worldwide for free using Truecaller.
Hunter - Find all the email addresses related to a domain
CallApp - Free Caller ID & Call Blocker app that allows mobile users to block phone calls, identify calls, blacklist unwanted callers and much more.
Snov.io - More leads. More sales. More revenue.
CallerSmart - CallerSmart is an application that is basically used for the purpose of looking up mystery phone numbers for free.
MailDump Verifier - Powerful Emails Verifying Tool that helps verify email address or validate email addresses