AnyMailFinder.com - Find anyone's email address
SIREN.io - Siren is an investigative intelligence platform.
Hunter - Find all the email addresses related to a domain
DataWalk - DataWalk is a software platform to connect numerous large data sets, both external and internal, into a single repository for fast visual analysis.
Mailmeteor - Send hundreds of personalized emails with Gmail.
sn0int - sn0int is a semi-automatic OSINT framework and package manager