SSL Certificate Checker
Connects over TLS and reads the certificate the server actually presents: who issued it, when it expires, which names it covers, and whether it validates against the public trust store.
About
This tool connects to the host over TLS and reads the certificate the server actually presents, rather than trusting a cached copy. You get the issuer, the validity dates with the days remaining, every name on the certificate, the chain as served, and whether it validates against the public trust store.
How to use
- Enter the hostname you visit in the browser, such as example.com.
- Submit and wait for the TLS handshake.
- Check the expiry, the hostname match and the trust result, in that order.
Frequently asked questions
Why does it say not trusted when the site loads fine?
Either the chain is incomplete, which some browsers repair by fetching the missing intermediate, or the certificate is self-signed. Browsers are more forgiving than the strict check used here.
What is a SAN?
A subject alternative name. Modern certificates list every hostname they cover there, and browsers ignore the older common name field entirely.
How much notice should an expiry give?
Thirty days is the usual warning threshold, and most certificates now last only a few months because of the maximum validity rules. Automating renewal is far safer than watching dates.
Does this test which protocol versions are enabled?
It reports the version and cipher that were negotiated, which is what a real visitor would get. It does not probe every protocol version in turn.