Free tools
Check a domain or URL instantly. All tools use the same checks as DomainWarn monitoring and query DNS directly at the authoritative name server.
SPF Checker
Free SPF record check and lookup: syntax, includes, the 10 DNS lookup limit and the closing qualifier. Shows whether your domain blocks forged senders.
Open tool →DMARC Checker
Free DMARC record check and lookup: policy (none, quarantine, reject), pct, reporting addresses and syntax errors. With recommendations for moving to p=reject.
Open tool →DNS Checker
Free DNS lookup straight from the authoritative name server: A, AAAA, CNAME, MX, TXT, NS and CAA records at a glance. No sign-up, every record explained.
Open tool →MX Checker
Free MX lookup: which mail servers receive for a domain, do they resolve, is the priority right? Detects missing and unreachable mail servers.
Open tool →SSL Checker
Free SSL certificate check: expiry date, issuer, chain, host name, alternative names and TLS version. Detects expired, self-signed and mismatched certificates.
Open tool →HTTP Header Checker
Free HTTP header check: HSTS, Content-Security-Policy, X-Content-Type-Options, X-Frame-Options, Referrer-Policy and Permissions-Policy with recommendations.
Open tool →Redirect Checker
Free 301 redirect check: every hop with status code and response time, from http to https, from www to non-www. Detects redirect chains, loops and 302s.
Open tool →DKIM Checker
Free DKIM record check and lookup: selector, key type, key length, syntax and revoked keys. Leave the selector empty to try common selectors automatically.
Open tool →DNSSEC Checker
Free DNSSEC test: DS record, resolver validation and broken signature chains. Shows whether validating resolvers like Google or Cloudflare reach your domain.
Open tool →MTA-STS Checker
Free MTA-STS check: DNS record, policy file, mode, max_age and whether your MX servers are covered. Shows whether inbound mail enforces TLS.
Open tool →TLS-RPT Checker
Free TLS-RPT record check: syntax, reporting addresses (rua) and common errors such as a missing record. Shows whether you get reports on TLS failures.
Open tool →BIMI Checker
Free BIMI record check: syntax, logo URL, SVG Tiny PS, VMC certificate and the DMARC prerequisite. Shows why your logo does not appear in Gmail.
Open tool →Blacklist Check
Free IP blacklist and domain blacklist check: mail server IPs, website IP and domain against Spamhaus, Spamcop, Barracuda, PSBL and SURBL. With delisting links.
Open tool →Domain Checker
Free domain check: expiry date, registrar, EPP status, transfer lock and name servers straight from the registry via RDAP. Warns about expiry and holds.
Open tool →Guides
For every tool the matching guides from daily agency work with client domains. Each one ends with a concrete record or a checklist.