Adapt is a B2B contact and company database provider across multiple industries. Adapt has 100 million business contacts, including industry-specific company database and contact information such as job title, direct dial, and email addresses.
It's affordable and they seem to be able to find a wide range of contact details. They have a nice Chrome extension which works well.
Clearbit is the marketing data engine for all of your customer interactions. Deeply understand your customers, identify future prospects, and personalize every single marketing and sales interaction.
Clearbit is a pretty big platform with a sizeable suite of prospecting tools. The Salesforce integration is seamless and makes the process of finding, capturing, and converting leads east and effective.