SSL Certificate

The certificate's common name and subject alternative names, the issuer, the validity dates and days remaining, the signature algorithm, and the chain of intermediate certificates.

The tool shows the exact expiry date and the number of days left, and warns when a certificate has expired or expires within two weeks.

Yes. Enter the host and set the port field — for example 8443 or 993 — and the tool reads the certificate presented on that port.

A server presents its leaf certificate plus intermediate certificates that link it to a trusted root. The root lives in the client trust store; a missing intermediate is a common cause of chain errors.

Subject Alternative Names list every host name a certificate is valid for. Modern browsers rely on the SAN list rather than the common name, so a certificate must include each domain it needs to secure.

A wildcard certificate such as *.example.com secures all direct subdomains of a domain with a single certificate. It does not cover the bare domain itself or deeper subdomains like a.b.example.com unless listed.

Often the server is not sending the intermediate certificates. Browsers can sometimes fetch or cache them, but stricter clients cannot, so include the full chain in your server configuration.

They differ in validation depth: Domain Validated confirms only domain control, Organization Validated verifies the organization, and Extended Validation performs the most thorough checks. All three provide the same encryption strength.