Apollo.io API
B2B sales intelligence and engagement platform API that provides contact and company search, enrichment, and automated email sequence execution from a database of 275M+ contacts.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
API key in request body is a common but weaker pattern than header-based auth — logs and URL history may capture keys. No scopes means a leaked key grants full account access including sequence enrollment and data export.
⚡ Reliability
Best When
An agent needs to discover, enrich, and engage B2B prospects end-to-end within a single platform without stitching together separate data and email tools.
Avoid When
You only need one narrow capability (e.g., email verification only) where a cheaper point solution would suffice, or your contacts are primarily consumer/SMB.
Use Cases
- • Searching for B2B contacts by job title, company, industry, or location for outbound prospecting agents
- • Enriching CRM records with phone numbers, email addresses, and firmographic data
- • Enrolling leads into automated email sequences triggered by agent workflows
- • Building targeted account lists based on technographic and firmographic filters
- • Syncing enriched contact data to Salesforce, HubSpot, or other CRMs via Apollo API
Not For
- • Consumer (B2C) contact data — database is entirely B2B professional profiles
- • Real-time phone number lookups with carrier-grade accuracy
- • Teams operating exclusively outside North America and Europe where data coverage thins
Interface
Authentication
API key passed as api_key in request body (POST) or as a query parameter. No fine-grained scopes — key has full account access. Key should be treated as a secret.
Pricing
Credit system governs data export and enrichment. API access is included in paid plans; some endpoints (sequences, dialer) require higher tiers. Free plan has meaningful API limits.
Agent Metadata
Known Gotchas
- ⚠ Some error conditions return HTTP 200 with an error body — agents must inspect response payload, not just status code
- ⚠ Credits are consumed on enrichment even when the result is empty/not found; agents should pre-validate before bulk enrichment
- ⚠ Sequence enrollment has no built-in deduplication — agents must check existing enrollments before adding contacts
- ⚠ Contact export pagination uses page/per_page params with a max of 25 results per page — agents need explicit pagination loops
- ⚠ GDPR opt-out data is not reliably reflected in the API — requires separate compliance checks for European contacts
Alternatives
Full Evaluation Report
Detailed scoring breakdown, competitive positioning, security analysis, and improvement recommendations for Apollo.io API.
Scores are editorial opinions as of 2026-03-06.