Certificate SAN Explorer

Connect to a TLS endpoint and list the DNS names published in its certificate Subject Alternative Name extension.

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Related Tools

Subdomain Finder

Search certificate transparency data for related hostnames.

CNAME Discovery

Discover CNAME records in use and identify likely linked services.

DKIM Selector Finder

Try common selectors and discover likely DKIM records.

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What Is a Subject Alternative Name in TLS?

Learn what a subject alternative name is in a TLS certificate, why SANs matter for hostname validation, and how SAN data helps with discovery and troubleshooting.

Fix CAA Record Errors Before Certificate Renewal

Learn how to fix CAA record errors, why certificate issuance gets blocked, and how to verify issue, issuewild, and parent-domain policy before renewal fails.