SSL certificate checker
Use this checker to see whether a public hostname presents a valid HTTPS certificate on port 443. It reads the certificate your visitors see, including the issuer, the names it covers, and how many days remain before expiry. The result also notes whether the certificate chain verifies against common trust stores and whether the name you entered matches the certificate subject or SAN list. That helps catch mismatched hostnames, expired certificates, and missing intermediate certificates before browsers show a warning. Enter a domain such as example.com or a full https URL. The check is read-only and does not install or renew anything on your server.
Questions about this checker
What does the SSL checker test?
It opens a TLS connection to port 443 on the hostname you enter and reads the presented certificate. You see the issuer, subject, alternative names, validity window, approximate days left, whether the chain verifies, and whether the hostname matches the certificate.
Is it safe to run this on my live site?
Yes. The checker performs the same kind of handshake a browser does when someone visits https://your-site. It does not change configuration, upload files, or store your page content.
Does it work with wildcard certificates?
If your certificate lists wildcard or additional hostnames in its SAN field, those names appear in the results. Hostname match uses the name you typed against the subject and SAN list.
What should I do if the certificate is expiring soon?
Renew the certificate with your CA or hosting panel before the expiry date, and set up automatic renewal. SiteMon Watch can email you two weeks before expiry if you add the site to monitoring.