Basic tool to extract domains/subdomains from URLs en masse
go get github.com/hakluke/haktldextract
cat urls.txt | haktldextract
Options:
-t threads (number of concurrent threads to use, default is 16)
-s subdomains (dump subdomains instead of base domains)
Example:
cat urls.txt | haktldextract -s -t 16 | tee ./subs.txt