Free website tool
SSL Certificate Checker
Check a site's SSL/TLS certificate: issuer, expiry date and days left, covered names, chain problems, TLS version and HTTP/2.
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What the SSL checker tests
We open a TLS connection to the domain on port 443, the same way a browser does, and read the certificate the server presents. Then we check what a browser would:
- Expiry: the exact end date and how many days are left.
- Name coverage: whether the name you entered is listed in the certificate, including wildcard rules.
- Chain of trust: whether the certificate chains to a root in the Mozilla CA store, and whether intermediates are missing.
- Protocol: the TLS version negotiated (1.3 or 1.2 is good) and whether the server offers HTTP/2.
The result reflects the server our DNS lookup picked. Sites behind several servers or a CDN can, rarely, serve different certificates from different machines.
Frequently asked questions
- What happens when an SSL certificate expires?
- Browsers stop the visitor with a full-page “Your connection is not private” warning, which most people won't click past. Crawlers and APIs fail outright, so search engines may stop crawling the site until it's fixed. Free certificates from Let's Encrypt last 90 days and renew automatically, so an expiring one usually means the renewal job is broken.
- What is an incomplete certificate chain?
- Your certificate is signed by an intermediate certificate, which is signed by a trusted root. The server must send the intermediate too. If it doesn't, desktop browsers often cope by fetching it themselves, but many phones, command-line tools, payment providers and crawlers fail. The fix is to install the full chain file your provider gives you, often named fullchain.pem.
- Does HTTPS affect SEO?
- Google uses HTTPS as a lightweight ranking signal, and Chrome labels plain HTTP pages “Not secure”. The bigger risk is a broken certificate: it blocks visitors and crawlers entirely, which costs far more traffic than the ranking signal is worth.