Free, fast diagnostic tools for DNS, email authentication, network security, and more.
Query A, AAAA, MX, TXT, NS, SOA, CNAME, PTR, CAA, SRV, TLSA, HTTPS, MTA-STS, BIMI and more. Results come directly from authoritative nameservers.
Query 7 global public resolvers simultaneously to see whether your DNS changes have propagated worldwide.
Verify the DNSSEC chain of trust. Check DS, DNSKEY, and RRSIG records to confirm cryptographic signing is properly configured.
Look up structured RDAP registration data for any domain or IP — registrar, status, expiry dates, nameservers, and contacts.
Detect your public IPv4 and IPv6 addresses with geolocation, ISP name, and a live map.
Send ICMP echo requests to any hostname or IP and see real-time round-trip times and packet loss statistics.
Trace the network path hop-by-hop with real-time results and geolocation data for each router along the route.
Check an IP address or domain against 15+ major DNS-based blocklists in parallel.
Inspect SSL/TLS certificate details, expiry date, SANs, key info, and certificate chain for any hostname.
View HTTP response headers and redirect chains. Highlights security headers and flags missing ones.
Test whether a site supports HTTP/2 and HTTP/3. Checks ALPN negotiation, Alt-Svc advertisement, HTTPS redirect, and HSTS configuration.
Test whether a TCP port is open or closed on any hostname or IP address. Grabs server banners for SSH, SMTP, FTP, and more.
Get a combined SPF + DMARC health grade (A–F) with a per-check breakdown and actionable recommendations for your domain.
Look up and validate SPF records for any domain. Recursively expands all include chains and flags errors.
Look up and validate DMARC records for any domain. Every tag is explained with validation status and warnings.
Look up and validate DKIM public keys for any domain and selector. Checks key size, flags, and configuration.
Paste raw email headers to trace the delivery path, check SPF/DKIM/DMARC results, and find routing delays.
Build a valid SPF record for your domain. Select email providers, enter IP ranges, and generate a ready-to-publish TXT record.
Build a valid DMARC record for your domain. Set policy, reporting URIs, and alignment options.
Validate MTA-STS DNS records and policy files. Check mode, max_age, MX coverage, and policy file reachability.
Validate BIMI DNS records, fetch and preview the SVG brand logo, and check VMC certificate URLs.