Apollo.io

Apollo is a B2B contact database plus an outbound email sequencer rolled into one platform. The database covers tens of millions of professional contacts with email addresses, phone numbers, and buyer intent signals.

AI-assisted sequencing writes personalized opening lines based on prospect data, and intent data shows which target accounts have been researching topics in your category recently. The free tier is unusually generous for the category: it includes monthly credits and access to most of the database, which is enough to actually evaluate the product on real outbound.

Apollo integrates with Salesforce, HubSpot, and Outreach, plus a LinkedIn extension that pushes prospects from search results into sequences with a couple of clicks.

Freemium model with a free tier including monthly credits, scaling to paid subscription per seat with higher credit limits and team features.

Best for B2B marketers and SDRs running outbound at growth stage who need extensive contact data without enterprise-level data tool pricing. Data coverage is strongest for North American and European mid-market companies.