An SSL/TLS certificate helps a browser verify the identity of a hostname and establish an encrypted HTTPS connection. This checker retrieves certificate details such as the subject, issuer, validity window, and other information available from the remote endpoint.
What to look for?
Confirm that the certificate covers the hostname you intended to test and that the expiry date has not passed. A valid certificate alone does not prove a website is trustworthy; it only addresses part of transport security and identity validation.
Common certificate problems
- Expired certificate.
- Hostname mismatch.
- Missing intermediate certificate in the served chain.
- Testing the wrong hostname after a DNS migration.
- Server clock or deployment mistakes.
Router admin pages are different
Local router interfaces often use self-signed certificates, which can trigger browser warnings even when you are connected directly to your own router. Verify that you are using the correct local address before bypassing any warning.
Separate certificate validity from website trust
A certificate check can show hostname coverage, issuer, validity dates, and certificate-chain information. That helps diagnose expiry and deployment mistakes, but a valid certificate only authenticates the TLS endpoint under the certificate system; it does not guarantee the website content or business is trustworthy.
Local router certificates are a different case
Router dashboards often use self-signed or locally issued certificates, so a browser warning can appear on a legitimate private address. Verify the gateway and device before proceeding; never ignore a certificate warning on an unexpected public site just because local routers sometimes generate them.