SSL Checker

An SSL certificate is the foundation of trust on the web. It's what enables HTTPS, what puts the padlock in the browser address bar, and what encrypts the connection between a visitor's browser and your server. SSL Checker examines the certificate on any domain and tells you whether it's valid, who issued it, what it covers, and — critically — when it expires.

Certificate expiration is a recurring operational problem that catches people off guard more often than it should. A certificate that expires silently turns your secure site into one that browsers flag with a full-page warning, telling visitors the connection isn't private. Traffic drops immediately. If the site handles transactions, sales stop. Most users won't click through a security warning — they'll just leave. SSL Checker gives you the expiration date so you can schedule renewal well in advance.

The tool also verifies the certificate chain — checking that the issuing certificate authority is trusted and that the intermediate certificates are properly configured. A broken chain causes browser warnings even when the certificate itself is technically valid. This is a common issue after certificate renewals where the intermediate certificate bundle isn't updated correctly on the server.

Subject Alternative Names (SANs) tell you which domains and subdomains the certificate actually covers. A certificate issued for example.com doesn't automatically cover www.example.com or shop.example.com unless those are explicitly listed. Running SSL Checker on all your active subdomains makes sure nothing is operating with an uncovered or expired certificate that you've lost track of.