UpLead is a B2B prospecting platform that provides B2B contact & company data. Features include real-time email verification, contacts in over 200 countries, 50+ search criteria, technology tracking, account based marketing, competitor intelligence, email pattern intelligence, social profile links, Salesforce & 12 other CRM integrations, and a robust API.
We like the intuitive user interface, and it's also nice how they flag contacts that are potentially not up-to-date, so you don't waste your credits!
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.