LeadFuze uses third party data partners and in-house crawling to aggregate, match and verify real-time company info, emails, mobile numbers, social profiles and more.
They have a cool feature called FuzeBot, which can be set on autopilot and drip new contacts into your CRM as it finds them.
RocketReach provides real-time verified data for 450 million professionals across 17 million companies, worldwide.
RocketReach is very user friendly, and generally their data is high quality. We like that it marks personal emails so you can assess whether it is appropriate to contact that person there.