365 User Portal : https://www.office.com/

365 Admin Portal : https://admin.microsoft.com

Azure Portal : https://portal.azure.com

AWS Console : https://console.aws.amazon.com/console

SMTP Test tool : https://www.gmass.co/smtp-test

DNS propagation Checker : https://dnschecker.org/

Password Generator : https://passwordsgenerator.net/

DNS Lookup : https://mxtoolbox.com/SuperTool.aspx

SPF Checker : https://www.dmarcanalyzer.com/spf/checker/

TreeSize : https://www.jam-software.com/treesize_free

IP scanner : https://www.advanced-ip-scanner.com

1pass : https://start.1password.com/signin

Retrieve Whole Zone Record : https://network-tools.com/nslookup/