crt.sh vs Subfinder: Side-by-Side Comparison (2026)
Features, pricing, ratings, and pros & cons — compared head-to-head.
crt.sh is a free external attack surface management tool. Subfinder is a free external attack surface management tool. Compare features, ratings, integrations, and community reviews side by side to find the best external attack surface management fit for your security stack.
CST VerdictBased on our analysis of NIST CSF 2.0 coverage, core features, integrations, company size fit, here is our conclusion:
Security teams doing threat intelligence or domain monitoring should use crt.sh as a free, fast way to spot certificate issuance anomalies that signal domain takeover or phishing campaigns before they scale. Certificate Transparency logs index roughly 15 billion certificates, giving you real-time visibility into what's been legitimately issued against your domains and competitors' infrastructure. Skip this if you need automated alerting or integration into your SIEM; crt.sh is a lookup tool, not a monitoring platform, and catching malicious certificates requires manual checks or custom scripting.
Reconnaissance teams conducting external attack surface mapping will get the most from Subfinder; its passive enumeration approach surfaces subdomains without triggering WAF alerts or leaving detectable scanning noise. With 12,248 GitHub stars and active community contributions, the tool consistently outpaces commercial alternatives on speed and accuracy across public DNS sources. Skip this if you need active probing, WHOIS integration, or post-enumeration validation; Subfinder stops at the list.
