Website Diagnostics
SSL Certificate Checker
Validate the certificate presented by a public hostname on the standard TLS port and inspect its useful identity and lifetime fields.
Check a TLS certificate
The server connects only to already resolved and validated public IP addresses. Every DNS candidate must be public; no arbitrary ports or protocols are accepted.
What a TLS certificate verifies
A browser-trusted certificate binds one or more hostnames to a public key through a trusted certificate authority. Successful validation means the chain is trusted, the certificate is currently within its validity window and its names cover the hostname checked.
Why SAN entries matter
Subject Alternative Name entries list the hostnames a modern certificate covers. A certificate can be otherwise valid but still fail when the requested hostname is missing.
Expiration and trust
After the valid-until time, clients should reject the certificate. An unexpired certificate can also fail because its issuer is untrusted, its chain is incomplete, or the hostname does not match.
What this result means
A valid result means the presented chain, hostname and dates passed this environment’s checks now. It does not certify the site’s content; days remaining are renewal context rather than a security score.