Certificate transparency monitor. Queries crt.sh to enumerate subdomains and certificates for a given domain.
Useful for passive recon.
go install github.com/Shinjio/ctmon@latestctmon -d <domain> [-since <days>] [-v] [-json] [-timeout <sec>]
# Basic lookup
ctmon -d example.com
# Last 30 days only
ctmon -d example.com -since 30
# JSON output, pipe to jq
ctmon -d example.com -json | jq '.[] | .Domain'
# Verbose with custom timeout
ctmon -d example.com -v -timeout 20