Castle - The easiest way to protect your users from getting hacked
Numverify - Global phone number validation and lookup API
Mail Dump - Powerful Extensions for email addresses extracting, verifying and finding
Antideo - Email, IP address and phone number validation API service
Truecaller - Find a person by a name or phone number worldwide for free using Truecaller.
RealValidito - Phone Validator | Free Phone Number Validation & Phone Number Lookup Service | Realvalidito