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SSL Certificate Checker
Check any domain's SSL certificate details and expiry
Free
No sign-up
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About this tool
Look up a domain's live SSL/TLS certificate — issuer, validity dates, days until expiry, and subject alternative names.
Frequently asked questions
Why does my SSL certificate expiry date matter?
An expired certificate causes browsers to show visitors a hard security warning and blocks HTTPS access entirely — checking days-until-expiry regularly lets you renew before it becomes a live outage.
What are subject alternative names (SANs)?
Additional hostnames a single certificate is valid for beyond the primary domain — e.g. a cert for "example.com" often also covers "www.example.com" via its SAN list.
Does this check the certificate on the live site, or just the DNS record?
It connects directly to the domain over HTTPS and reads the actual certificate being served right now — the same thing a visitor's browser sees.