See every certificate in a site's SSL/TLS chain — the leaf certificate plus every intermediate up to the root — with subject, issuer, and validity dates for each.
Frequently asked questions
SSL Certificate Checker shows just the site's own (leaf) certificate; this tool shows the entire chain — every intermediate certificate up to the root — useful for diagnosing "incomplete chain" browser warnings.
If a server doesn't send its intermediate certificates, some browsers and clients (especially older ones, or non-browser tools) may fail to verify the certificate even though it's technically valid.