Subdomain lookup tool using https://subdomainfinder.c99.nl/
for install git clone https://github.com/777388/SubdomainsExtension.git
go into chrome://extensions and load unpacked the subdomainsextension folder
right click a page and hit Subdomains, the hostname of the page you were on will be hashed in the url after #. just copy that and place it in the searchh bar.