Zoominfo

ZoomInfo is the enterprise heavyweight of B2B data — the largest contact and company database with intent signals, technographic data, and org chart intelligence. For agents, ZoomInfo's data depth is unmatched: direct-dial phone numbers, verified emails, company hierarchy data, technology stack detection, and buyer intent signals. The API covers person search, company search, enrichment, and intent data retrieval. However, ZoomInfo is primarily enterprise-priced with sales-gated access — there's no self-serve signup or free tier for API access. This makes it the least agent-accessible enrichment platform in this category. Agents that do have ZoomInfo access benefit from superior data coverage and freshness for enterprise contacts. The API is functional but the access barrier is the defining constraint.

Authentication uses a JWT flow: POST username/password to /authenticate, receive a JWT token, use as Bearer token on subsequent requests. Tokens expire and must be refreshed. No API key-based auth for simplicity. Access is gated behind an enterprise contract — no self-serve API key generation. This means agents can't start building against ZoomInfo without a sales conversation and contract. Permissions are tied to the user's subscription level and data entitlements. Data export restrictions may apply based on contract terms. For agents, the enterprise gate is the primary friction: the technical integration is straightforward once access is granted, but obtaining access requires procurement.

API documentation at api-docs.zoominfo.com provides endpoint reference with parameters and response examples. The documentation is adequate but assumes enterprise context — it doesn't address lightweight or experimental integration patterns. No official SDKs for public use. Documentation access may require authentication. Getting started requires the enterprise onboarding process, which includes API credential provisioning and data entitlement configuration. Integration guides for CRM platforms (Salesforce, HubSpot) are available. Developer support is through enterprise support channels, not community forums. For agents, ZoomInfo's documentation quality is less relevant than its access model: the technical docs are fine, but the enterprise procurement barrier is the real constraint.

REST API with JSON payloads. Person Search: POST with filters for name, email, title, company, location, seniority, department, and more. Company Search: POST with filters for name, domain, industry, revenue, employee count, and technographic criteria. Enrichment endpoints accept identifiers and return full profiles. Intent data API surfaces buying signals for specific topics. The API uses a JWT-based authentication flow requiring username/password exchange for a bearer token. Pagination uses offset/limit. The data model is comprehensive: person records include direct phone numbers, verified emails, and employment history. Company records include technographic data, funding, and organizational hierarchy. Bulk export APIs handle large data pulls. The API design is adequate but not modern — it reflects enterprise data platform conventions rather than developer-first API design.

API errors return JSON with status and error fields. HTTP status codes follow conventions. Rate limits are contract-dependent — not publicly documented. The most common 'error' agents encounter is entitlement-based: queries for data outside the subscription's coverage return limited results, not errors. This means agents must understand their contract's data scope. JWT token expiry requires refresh logic. Search queries with no results return empty arrays, not errors. Data accuracy for person records degrades over time as people change jobs — ZoomInfo refreshes data periodically but stale records exist. Bulk export jobs are async with polling for completion. The API is generally reliable within contracted entitlements.