Check Tools
A collection of great checker-style tools to help you validate and verify.
22 tools
BIMI Checker
Check a domain's BIMI record, which shows your brand logo next to authenticated email in the inbox.
OpenBlacklist Checker (DNSBL)
Check whether an IP or domain appears on email blocklists (DNSBL) that hurt the deliverability of your messages.
OpenCAA Checker
Check a domain's CAA records to see which certificate authorities are allowed to issue its SSL certificates.
OpenDKIM Checker
Look up a domain's DKIM public keys by selector. Provide your selectors or let common provider selectors be probed.
OpenDMARC Checker
Look up and analyse a domain's DMARC record —policy (p=), reporting (rua), percentage and alignment— with actionable warnings.
OpenDNS Lookup
Find A, AAAA, CNAME, MX, NS, TXT and SOA DNS records for a host.
OpenDNS Propagation Checker
Check a domain's DNS propagation by querying several resolvers worldwide and comparing their answers.
OpenDNSSEC Checker
Check whether a domain is protected by DNSSEC, inspecting DS/DNSKEY records and validation of the chain of trust (AD flag).
OpenDomain Health Report
Audit a whole domain in one query: DNS, SPF, DKIM, DMARC, DNSSEC, CAA, TLS certificate and security headers, with a prioritised list of what to fix.
OpenEmail Auth Checker (SPF, DKIM, DMARC)
Audit a domain's SPF, DKIM and DMARC records and get a graded report with fixes to stop email spoofing.
OpenEmail Header Analyzer
Analyze an email's headers in your browser and review the Received route with delays plus the SPF, DKIM and DMARC verdicts.
OpenHTTP Security Headers
Analyse a site's HTTP security headers (HSTS, CSP, X-Frame-Options and more) and get a grade plus the ones you are missing.
OpenMTA-STS Checker
Check a domain's MTA-STS policy (DNS record and .well-known file) that enforces TLS for inbound email.
OpenMX Lookup
Look up a domain's mail servers (MX records), their priority and the IPs they resolve to.
OpenSPF and DMARC Record Generator
Build your domain's SPF and DMARC records with a wizard: pick your email providers and get the TXT ready to publish, with warnings about the mistakes that break mail.
OpenSPF Checker
Analyse a domain's SPF record, detect its trailing qualifier (-all, ~all) and count DNS lookups against the limit of 10 (RFC 7208).
OpenSubnet Calculator
Work out network, broadcast, host range, netmask and wildcard from CIDR notation, for IPv4 and IPv6. Split a block into subnets. All in your browser.
OpenTLS-RPT Checker
Check a domain's TLS-RPT record to see whether it receives reports about email TLS encryption failures.
OpenWHOIS Lookup
Look up a domain's registration data (registrar, creation and expiry dates, name servers and status) straight over the WHOIS protocol.
OpenIP Lookup
Get approximate details about an IP address.
OpenReverse IP Lookup
Takes an IP address and finds the domain or host (PTR record) associated with it, with geolocation and provider. Free and no sign-up.
OpenSSL Lookup
Get all the details you can about an SSL certificate.
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