https://shodan.io/ == servers
https://google.com/ == dorks
https://wigle.net/ == wifi networks
https://grey.app/ == code search
https://onyphe.io/ == server
https://viz.greynoise.io/ == threat intelligence
https://censys.io/ == server
https://hunter.io/ == email addresses
https://fofa.info/ == threat intelligence
https://zoomeye.org/ == threat intelligence