$ man apollo-wiki/api-quick-reference

Referencebeginner

Apollo API Quick Reference

Endpoints, env setup, common errors, and rate limits card


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Environment Setup

Add to your .env file: APOLLO_API_KEY=your_key_here. Get your key from Apollo Dashboard > Settings > API Keys. In Python: import os; api_key = os.environ['APOLLO_API_KEY']. Base URL for all endpoints: https://api.apollo.io. All requests are POST with JSON body. Include api_key in the request body, not as a header.
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Key Endpoints

People Search: POST /v1/mixed_people/search - Search contacts by title, seniority, company, location, industry. Returns up to 100 results per page.

Organization Enrichment: POST /v1/organizations/enrich - Enrich a company by domain. Returns firmographics, tech stack, funding, employee count.

People Enrichment: POST /v1/people/match - Match a single person by name + company or email. Returns full contact record.

Bulk People Match: POST /v1/people/bulk_match - Match up to 10 people per request. More efficient than individual calls.
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Rate Limits

Free tier: 10,000 credits/month. 100 requests/minute. 1 credit per contact returned in search, 1 credit per enrichment call.

Basic ($49/mo): 60,000 credits/month. Higher rate limits.

Professional ($99/mo): 120,000 credits/month. Intent data, buying signals.

If you hit a rate limit, Apollo returns HTTP 429. Back off for 60 seconds and retry. In production, use a simple sleep-and-retry pattern with exponential backoff. Log every 429 so you can tune your batch sizes.
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Common Errors

401 Unauthorized: Bad API key. Check your .env file and make sure the key is not expired.

422 Unprocessable Entity: Invalid request body. Usually a missing required field or wrong data type. Check that arrays are arrays, not strings.

429 Too Many Requests: Rate limited. Wait 60 seconds and retry. If persistent, reduce batch size or add delays between requests.

Empty results: Not an error - your filters are too narrow. Broaden seniority levels, add more title keywords, or expand the company size range. Apollo returns what matches, not what you expect.

related entries
Apollo API ArchitectureThe Hacker Track: API + Supabase + Claude CodeApollo to Supabase Data Warehouse
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