ONLINE TEST OF A ZONE TRANSFER THAT WILL ATTEMPT TO GET ALL DNS RECORDS FOR A TARGET DOMAIN. THE ZONE TRANSFER WILL BE TESTED AGAINST ALL NAME SERVERS (NS) FOR A DOMAIN.
https://hackertarget.com/zone-transfer/
DOMAIN NAME SYSTEM SECURITY EXTENSIONS (DNSSE)
https://dnssec-analyzer.verisignlabs.com/
EXIF GEOLOCATION DATA NOT STRIPPED FROM UPLOADED IMAGES
http://exif.regex.info/exif.cgi
TO TEST FOR SECURITY HEADERS
https://securityheaders.com/
GOOGLE DORKS
https://dorks.faisalahmed.me/
CERTIFICATE CHECKER
https://www.sslchecker.com/sslchecker
PASSIVE INFORMATION GATHERING
https://spyse.com
FREE DOMAIN RESEARCH TOOL THAT CAN DISCOVER HOSTS RELATED TO A DOMAIN