Clearbit - Clearbit provides Business Intelligence APIs
Albacross - The world's first free B2B Lead Generation Network. Albacross help companies master their B2B digital marketing with Lead Generation and targeted marketing
Memotoo - Memotoo allows you to sync your data (contacts, calendar, tasks, .) with phones (iPhone, Android, Samsung, ..
Hunter - Find all the email addresses related to a domain
Google Contacts - Google Contacts is Google's contact management tool that is available in its free email service Gmail, as a standalone service, and as a part of Google's business-oriented suite of web apps Google Apps.
Upscribe - Embeddable lead generation forms for Medium