SSL Certificate Checker
Check a certificate's expiry, issuer and whether it actually covers the hostname.
About this tool
Connects to a host over TLS and reads the certificate it presents: when it expires, who issued it, which names it covers, and whether the chain is complete.
Expiry is the outage that is completely predictable and still happens all the time. Nothing degrades first — every browser refuses the site at the same moment, and the people who could fix it often cannot reach the admin panel either, because that is behind the same certificate.
The other common failure is quieter: a certificate that is valid but does not cover the name people actually type. A certificate for `example.com` does not cover `www.example.com` unless it says so.
Common questions
How long before expiry should I renew?
Automate it and stop thinking about it. Let's Encrypt certificates last 90 days and renew at 30 by default. If you are renewing by hand, treat three weeks out as the deadline, not the reminder.
Does an expired certificate affect SEO?
Severely, but indirectly. Browsers show a full-page warning almost nobody clicks through, so traffic stops. Crawlers cannot fetch the site either, so pages start dropping out of the index.
Why does my certificate not cover www?
Because a certificate covers exactly the names listed on it. example.com and www.example.com are different names. You need both listed, or a wildcard — this tool shows you which names are actually on it.
What is an incomplete chain?
The server sends its own certificate but not the intermediate that links it to a trusted root. Desktop browsers often paper over this by fetching the missing piece; mobile browsers and API clients frequently do not, so it fails for some visitors and not others.