SSL Checker Documentation

Check an SSL certificate's expiry date, issuer, covered hostnames, chain of trust, and TLS version for any domain.

SiteIndex opens a TLS connection to the domain on port 443 using SNI, reads the certificate chain the server presents, and verifies it against trusted root authorities. It reports expiry and days remaining, the issuer, subject alternative names, whether the hostname matches, the negotiated TLS version and cipher, and whether HTTP/2 is offered via ALPN.

• Check when a certificate expires and confirm auto-renewal worked.
• Diagnose browser security warnings caused by a hostname mismatch or missing intermediate certificate.
• Confirm a new certificate covers every subdomain you need (www, api, etc.).

Input

A public website, domain, or network value required by the check.

Output

A result shown in the browser that can be reviewed or copied where supported.

• Results depend on the input, browser, network, and external service involved.
• This tool is informational and does not replace specialist diagnostics.

The requested public target is sent to SiteIndex only as needed to perform the check. SiteIndex does not require an account or intentionally store the target as a report. See the Privacy Policy for analytics and retention details. Read the Privacy Policy.