Hunter.io API
Email finder and verification API that discovers professional email addresses by domain or name, verifies deliverability, checks for disposable or catch-all configurations, and returns confidence scores. Used for B2B sales prospecting and outreach automation.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
HTTPS enforced. API key passed as query parameter exposes key in server logs and URL history - prefer header-based auth where possible (Hunter does not support header auth). No scope granularity; single key grants full account access. No IP allowlist feature documented.
⚡ Reliability
Best When
An agent needs to find and verify professional email addresses for B2B outreach or CRM enrichment, and operates in regions where GDPR basis for processing is established.
Avoid When
You are targeting EU individuals without clear legitimate interest basis, need non-email contact data, or have a monthly volume exceeding plan search limits.
Use Cases
- • Finding professional email addresses for sales outreach agents given a company domain
- • Verifying email deliverability before sending automated campaigns
- • Discovering all publicly-known emails at a target domain for company mapping
- • Enriching CRM contact records with verified email addresses
- • Filtering out disposable and catch-all email addresses before list import
Not For
- • Consumer or personal email lookups
- • Phone number, LinkedIn, or social media enrichment
- • Jurisdictions where data brokering without consent is legally prohibited
Interface
Authentication
API key passed as query parameter (api_key=YOUR_API_KEY). No OAuth, no scopes. Single key grants full account access. Keep server-side only.
Pricing
Free tier is suitable for prototyping only. Monthly search quota resets on billing date (not calendar month). Unused searches do not roll over on free plan. Paid plan pricing updated periodically - verify current pricing on site.
Agent Metadata
Known Gotchas
- ⚠ Monthly quota resets on billing date, not calendar month - quota tracking must account for this offset
- ⚠ Domain Search returns up to 100 results per page; use offset parameter for pagination on large companies
- ⚠ Email Finder returns status: 'found', 'guess', or 'notfound' - agents should handle 'guess' as low-confidence and threshold by score field
- ⚠ Email verification result accept_all: true means the server accepts all addresses - verification is unreliable for these domains
- ⚠ GDPR: finding and storing EU individual emails may require documented legitimate interest - Hunter provides data removal requests
Alternatives
Full Evaluation Report
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Package Brief
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Score Monitoring
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Scores are editorial opinions as of 2026-03-06.