SSL Certificate Checker

Three things that together decide whether browsers accept the certificate: that it's within its validity window (not expired and not future-dated), that it covers the hostname you entered (via its Common Name or Subject Alternative Names), and that its chain links up to a trusted certificate authority. It also shows the issuer, serial number, validity dates and the full SAN list so you can see exactly which names the certificate is valid for.

Most checkers just fail when a certificate is expired, self-signed or for the wrong host. This one connects without rejecting the certificate, so it can show you what's actually wrong — the expiry date, the mismatched names, or the trust error — which is exactly what you need to fix it. The trust verdict is reported separately, so a broken cert is clearly flagged rather than silently accepted.

Expired certificates are one of the most common and most embarrassing outages — the whole site goes untrusted in every browser at once. This tool gives you a point-in-time check; Uptimeify monitors your certificates continuously and warns you well before they expire, so a renewal never slips through. That's the difference between checking once and never being caught out.