Clearbit

Clearbit (now part of HubSpot) provides B2B data enrichment with a focus on data quality. The core APIs are Person (email → full profile: name, title, company, social profiles), Company (domain → firmographics: employee count, revenue, industry, tech stack), and Reveal (IP → company identification for anonymous visitors). For agents building lead qualification, CRM enrichment, or account-based marketing workflows, Clearbit's data quality has historically been strong — the HubSpot acquisition adds even more data coverage. The API design is clean and purpose-built for enrichment use cases. The combined Person+Company lookup returns both person and company data in a single call. Prospecting API enables filtered searches similar to Apollo. Main consideration: post-HubSpot acquisition, pricing and access model may evolve.

REST API at person.clearbit.com, company.clearbit.com, and reveal.clearbit.com. Person enrichment: GET to /v2/people/find?email={email} returns comprehensive profile data. Company enrichment: GET to /v2/companies/find?domain={domain} returns firmographic data with tech stack, employee count, revenue range, and industry classification. The combined endpoint at /v2/combined/find returns both person and company data. The API supports streaming mode — if data isn't immediately available, it returns 202 Accepted and delivers results via webhook. This async mode is useful for agents processing batches where some lookups require data sourcing time. Prospector API at /v1/people/search enables filtered contact searches. Response schemas are well-defined and consistent across endpoints.

API responses use standard HTTP status codes: 200 for found, 404 for no match, 422 for invalid input, 429 for rate limits. The 202 Accepted status (async/streaming mode) requires agents to handle webhook delivery or polling for results — not all lookups return immediately. Rate limits are per-API and per-second, with plan-specific allocations. The main quality consideration: enrichment coverage varies by person/company. C-level executives at large companies have high data coverage; individual contributors at small companies may return 404 or sparse results. Agents should handle partial enrichment results and 404s gracefully — both are normal operating conditions, not errors. Data freshness varies; some records may be months old.

API key authentication via Bearer token header or as username in Basic Auth (password empty). Keys are generated in the Clearbit dashboard. No fine-grained permission scoping — the key grants access to all APIs the account is subscribed to. No OAuth for third-party integrations. Usage is tracked per-API (person, company, reveal) with plan-based limits. Webhook authentication uses a signing secret for payload verification. The API doesn't expose PII creation — it only returns existing public/semi-public data, but agents must still handle enriched data in compliance with privacy regulations. No temporary credentials or key rotation mechanism. For agents, one API key per integration is the standard pattern.

API documentation is clean and well-structured with endpoint reference, response schema documentation, and integration guides. The documentation includes data dictionaries describing every field in person and company responses — essential for agents mapping enrichment data to their own data models. Client libraries exist for Ruby (official), Node, and Python (community). Webhook documentation covers the async enrichment flow. The HubSpot acquisition may result in documentation migration — agents should monitor for changes. Integration guides for common CRM and marketing platforms provide patterns that agents can adapt. For agents, the combined endpoint documentation and data dictionary are the most valuable starting points.