$ man apollo-wiki/api-architecture

☾

Apollo has a large API surface, but for GTM sourcing you only need two endpoints. POST /v1/mixed_people/search is your people search - filter by title, seniority, company size, industry, location, and dozens of other fields. It returns contacts with emails, phone numbers, and company data attached. POST /v1/organizations/enrich takes a domain and returns full company firmographics - employee count, revenue, funding, tech stack, industry classification. Those two endpoints cover 90% of what you need for sourcing and qualification.

PATTERN

Apollo uses API key authentication. You pass your key as an api_key parameter in the request body (POST) or as a query parameter (GET). No OAuth, no token refresh, no complex auth flow. Get your key from Settings > API Keys in the Apollo dashboard. Store it in your environment variables as APOLLO_API_KEY. That is the entire auth setup.

CODE

The people search endpoint returns a people array with each contact containing: id, first_name, last_name, title, seniority, email, organization (nested company object with domain, employee count, industry). The pagination object gives you page, per_page, and total_entries for batching through large result sets. Each page returns up to 100 results. Response is standard JSON - no weird nested structures or inconsistent field names.

PRO TIP

Apollo's free plan gives you 10,000 credits per month. A people search costs 1 credit per contact returned. An organization enrichment costs 1 credit. That means you can search and qualify 10,000 contacts per month for free. For comparison, Clay charges credits for every enrichment provider call, and their free tier is much smaller. If you are building a GTM pipeline on a budget, Apollo sourcing + Supabase storage + Claude Code scripting gives you a production-grade pipeline at near-zero cost.