Generate a wordlist from a list of already discovered subdomains, by splitting each one on its . labels. Feed it subdomains you already found (e.g. from Roots, subfinder, amass, etc.) and it prints the individual words that make them up — useful as a permutation/bruteforce wordlist for finding more subdomains.

go install -v github.com/kenjoe41/goSubsWordlist@latest

goSubsWordlist reads subdomains from stdin, one per line, and prints words to stdout:

cat subdomains.txt | goSubsWordlist > words.txt

For dev.api.example.com, it prints dev and api — the labels below the registered domain. The registered domain (example.com) is skipped by default; pass -iR to include it too:

cat subdomains.txt | goSubsWordlist -iR > words.txt

Output is deduplication-free and unsorted by design — pipe through sort -u if you need a unique, sorted wordlist:

cat subdomains.txt | goSubsWordlist | sort -u > words.txt

• -top N flag: output only the N most frequently occurring words (e.g. -top 1000). Requires in-memory word-occurrence tracking, which may not scale well for very large subdomain lists — needs benchmarking before landing.