Antideo - Email, IP address and phone number validation API service
Verifier - Weed out disposable, non-existent domains or invalid emails.
Numverify - Global phone number validation and lookup API
Email Verification on Google Sheets - An add-on for email verification directly in Google Sheets
RealValidito - Phone Validator | Free Phone Number Validation & Phone Number Lookup Service | Realvalidito
Email List Verify - The Fastest Way to Improve Email List Deliverability and ROI