NeverBounce - Real-time email verification and cleaning to ensure emails never bounce.
ZeroBounce - Removes invalid emails from your list to prevent email bounces from ruining your deliverability.
Email List Verify - The Fastest Way to Improve Email List Deliverability and ROI
Email YoYo - Email YoYo is an list cleaning and real-time email verification API to verify email addresses online.
BriteVerify - Email Validation & Email Verification reduces bounce rates up to 98%. Rapidly verifying email addresses has never been easier, just drag drop and deliver!
Email Checker - Email Checker offers a real-time API and bulk validation for list cleaning.