SSL certificate checker
Check whether a website's certificate is trusted by browsers, which names it covers, who issued it and when it expires.
What the certificate does
The TLS certificate proves to browsers that they are talking to the real website and encrypts the connection. Browsers warn visitors, or block the page, when the certificate is expired, untrusted or issued for another name.
How this check works
We connect to the website on port 443 as a browser would, read the certificate it presents, and check it a second time against the trusted certificate authorities. We only connect to public addresses.
Questions
- How often do certificates expire?
Most certificates last 90 days (Let’s Encrypt) to about a year (paid certificates), and the industry is moving to shorter lifetimes. Automatic renewal is the safe way to avoid an expired certificate.
- Why does a valid certificate show a warning on my domain?
The certificate must list the exact name visitors type. A certificate for example.com does not cover www.example.com unless it includes it, or a wildcard such as *.example.com.
- What does TLSv1.3 mean?
It is the protocol version used for the connection. TLS 1.3 and 1.2 are current; older versions are disabled by modern browsers.