We use Apollo.io's API for contact data. The free people search uses their api_search endpoint (no credits consumed), and email reveals use their people/match e

We use Apollo.io's API for contact data. The free people search uses their api_search endpoint (no credits consumed), and email reveals use their people/match endpoint. Apollo maintains one of the largest B2B contact databases — we're essentially a focused interface on top of their data, optimized for job seekers rather than salespeople.