Sending emails to invalid addresses is the fastest way to destroy your sender reputation. Here are the top APIs to keep your B2B lists clean and your bounce rate low.
If you are building a B2B SaaS or a lead generation tool, "Deliverability" is your most valuable asset. One bad batch of emails can land your domain in the spam folder permanently. These 5 APIs are the industry standard for verifying emails before you hit send.
Owned by Twilio, SendGrid is the giant of the email world. Their validation API is powered by the massive amount of data they process daily. It uses machine learning to predict validity scores, which is perfect for enterprise-grade applications.
ZeroBounce is widely regarded as the most accurate verifier for difficult B2B emails. It excels at detecting "Spam Traps" and "Abuse Emails" (users who frequently mark mail as spam). It also provides an "Email Scoring" AI system.
Abstract focuses purely on the developer experience. Their API is lightweight, extremely fast, and easy to integrate into sign-up forms to block fake users in real-time. It checks MX records and SMTP configuration instantly.
Hunter is famous for finding emails, but their Verifier API is equally powerful. It is specifically optimized for professional/business domains. If you are validating `@gmail.com` addresses, use another tool. If you are validating `@oracle.com`, use Hunter.
If you have a database of 100,000 users that you haven't emailed in a year, NeverBounce is your best bet. They offer excellent bulk cleaning rates and a "Sync" feature that can automatically clean your HubSpot or Salesforce data daily.