ZeroBounce
Email validation and deliverability API that verifies email addresses in real-time or in batch, scoring them on validity, bounce risk, spam traps, and abuse patterns.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
API key auth. Email addresses are PII — GDPR applies to email validation. SOC2 Type II. Data minimization practices. Email validation results contain data about real people.
⚡ Reliability
Best When
You need high-accuracy email validation with detailed scoring (bounce type classification, spam trap detection) and want a well-documented API with SDKs in multiple languages.
Avoid When
You only need basic syntax validation (do that client-side for free) or you're looking for a free email validation service at scale.
Use Cases
- • Real-time email validation at form submission to prevent bad emails entering your database
- • Batch validation of email lists before sending marketing campaigns
- • Scoring email quality to identify temporary/disposable addresses
- • Abuse and spam trap detection to protect sender reputation
- • Email append — finding email addresses for known contacts
Not For
- • Email sending — this is validation only, not an ESP
- • SMTP testing or email deliverability testing beyond validation
- • Domain-level DNS checks without email-level verification
Interface
Authentication
API key as query parameter in all requests. Single key per account. Credits-based system — each validation consumes credits.
Pricing
Credit-based system. Credits don't expire on paid plans. Volume discounts significant at scale. Monthly subscription plans also available.
Agent Metadata
Known Gotchas
- ⚠ API key in query parameter exposes it in server logs — use environment variable management carefully
- ⚠ Credits are consumed on each validation even for unknown results — budget accordingly
- ⚠ Catch-all domains (where server accepts all emails) cannot be fully validated — result is 'catch-all'
- ⚠ Batch file validation is asynchronous — must poll for completion or use callback URL
- ⚠ Results include sub-status codes (e.g., 'mailbox_not_found', 'failed_smtp_connection') — parse sub-status for detailed logic
- ⚠ Free credits (100) are consumed quickly in testing — budget for paid credits before production
Alternatives
Full Evaluation Report
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Scores are editorial opinions as of 2026-03-07.