SSL Certificate Checker

Check a site's HTTPS certificate: whether browsers will trust it, when it expires, which names it covers and which CA issued it.

FAQ

What does 'unable to verify' mean?
The server didn't send the intermediate certificates, or the certificate was issued by a CA browsers don't trust. Install the full chain your CA provides.
How do I avoid an expired certificate?
Turn on auto-renewal with your host or CA, and add a SiteUD monitor: it emails you before the certificate expires.