SSL Certificate Checker
Inspect a site's SSL/TLS certificate, issuer, and expiry.
Inspect a Website's SSL Certificate
Enter a domain and this tool opens a TLS connection to it on port 443 and reports the certificate it presents — who issued it, when it expires, how many days remain, the domains it covers, and whether the chain is trusted.
What you get
- Issuer and common name
- Valid-from and valid-to dates with days remaining
- TLS protocol version and serial number
- Subject Alternative Names (covered domains)
Expiry warnings
An expired certificate makes browsers show a security warning and blocks visitors. The checker flags certificates that have expired or that expire within two weeks so you can renew in time.
Why monitor certificates?
SSL/TLS certificates secure the connection between browsers and your site and typically last 90 days to a year. A lapsed certificate breaks HTTPS and erodes trust, so checking expiry dates ahead of time prevents outages.
Untrusted certificates
The checker still reports details for self-signed or untrusted certificates and tells you the chain was not verified, which is useful for diagnosing staging environments and misconfigured intermediate certificates.
Frequently Asked Questions
Common questions about the SSL Certificate Checker.