SSL Certificate Checker
About this tool
SSL Checker fetches real certificate info via TLS connection, including certificate chain visualization, server details, validity period and SAN domains. Supports custom ports.
Common uses: monitoring certificate expiry, troubleshooting HTTPS issues, verifying cert configuration.
Frequently asked questions
What does this tool check?
It connects to the domain and reports the certificate's issuer, validity dates, days remaining, the full chain and the negotiated TLS version and cipher.
Why does a valid site show a warning?
Common reasons are a certificate expiring soon, an incomplete chain or a hostname mismatch. The result explains which one applies.
Is this check done in my browser?
No β checking a TLS certificate needs a server-side connection, so this tool makes the request on the server. We don't store the domains you check.