Apollo API
Apollo ships a self-serve REST API on paid plans covering people and company search, enrichment, and sequences, with an OpenAPI spec, llms.txt, and an MCP server. API calls burn plan credits, and advanced endpoints plus higher rate limits are gated to Organization or custom tiers.
Frequently asked questions
Apollo scores A on the API Report Card. Apollo ships a self-serve REST API on paid plans covering people and company search, enrichment, and sequences, with an OpenAPI spec, llms.txt, and an MCP server. API calls burn plan credits, and advanced endpoints plus higher rate limits are gated to Organization or custom tiers.
Apollo has a workable official integration path. Most engineering teams can build against it directly. Open API: self-serve, documented, with SDKs
Apollo.io is an AI-powered B2B sales intelligence and sales engagement platform that bundles a 230M+ contact / 30M+ company database with multichannel outbound sequencing (email, dialer, LinkedIn), meeting scheduling, conversation intelligence, deal management, and CRM enrichment into a single end-to-end go-to-market product.
Vertical: B2B sales intelligence / sales engagement / outbound prospecting (horizontal SaaS, not industry-specific). SDRs and AEs build prospect lists by filtering Apollo's 230M+ contact database on title, seniority, department, company size, industry, technographics, funding stage, and buyer intent signals, then push qualified contacts into multichannel sequences (email steps, LinkedIn touches, dialer calls, manual tasks).
Apollo reports 600,000+ companies using the platform and holds 4.7/5 across ~9,000 G2 reviews, putting it firmly in the top tier of sales intelligence tools by install base and review volume.
Yes, for any B2B sales org running outbound on Apollo, it is the system of record for the entire prospecting and engagement dataset: the full prospect database with custom fields and lists, every sequence (steps, copy, A/B tests, send schedules) with enrollment state, every email send with open/click/reply history, every dialer call with recordings and AI-generated summaries, every LinkedIn touch logged through the extension, meeting bookings and scheduling state, lead scoring and intent signals, CRM sync mappings to Salesforce/HubSpot/Pipedrive, and the enriched contact/company data that drives the entire pipeline.
Founded 2015 in San Francisco as ZenProspect by Tim Zheng, Ray Li, and Roy Chung. Rebranded to Apollo.io in 2019 and pivoted from a pure prospecting tool to a unified sales platform.
Per-minute, per-hour, and per-day API rate limits are restrictive and vary by plan, frequently throttling high-volume enrichment and sync jobs. API calls consume credits at exorbitant rates, bulk enrichment and phone-number lookups burn through monthly credit pools quickly and trigger overage charges. Full sourced list under Sources below.
Common alternatives include ZoomInfo, Outreach, Salesloft, HubSpot Sales Hub, Cognism, Lusha. Graded alternatives appear under "More from the report card" below.
Grades measure one thing: can a customer's engineering team get their own data out programmatically? We check six things (whether a real API exists, how access is gated, data coverage, auth quality, docs and developer experience, and stability) and roll them into a letter grade. Grades get re-verified, and they only move on evidence.