AnyMailFinder.com - Find anyone's email address
sn0int - sn0int is a semi-automatic OSINT framework and package manager
Hunter - Find all the email addresses related to a domain
Lampyre - Lampyre - an efficient data analysis and OSINT multi-tool for everyone.
GitHub Email Finder - Find the email of any GitHub Developer using their GitHub username.
SIREN.io - Siren is an investigative intelligence platform.