DMARC, SPF & DKIM analysis, phishing site detection, and CT log subdomain search — all in one place, free, no sign-up required.
Check your domain's SPF, DMARC, DKIM and MX setup. Detects the SPF 10-lookup overflow that silently breaks authentication.
Analyse a domain for phishing indicators: brand impersonation, lookalike domains, suspicious keywords and DNS patterns.
Find a domain's subdomains from Certificate Transparency logs. Check each subdomain's DMARC on the spot.
Certadomain is a free, registration-free domain security toolkit. All checks are DNS-only — no page fetching, no API keys, no data stored beyond a short cache.
The DMARC checker implements RFC 7489 §6.6.3 subdomain inheritance with PSL-based org-domain detection, and includes a recursive SPF lookup counter to catch the 10-lookup overflow that silently invalidates authentication. Japanese internationalised domain names (IDN) are supported via IDNA encoding.
Certificate Transparency subdomain results merge two independent sources (crt.sh and certspotter) in parallel, so either source succeeding is enough to return results.