Security and certificates
Online SSL Certificate Checker
Inspect an SSL/TLS certificate, its validity, dates, issuer and covered domains.
SSL/TLS guide
What is an SSL/TLS certificate?
An SSL/TLS certificate enables encrypted HTTPS connections and helps verify the identity of a server.
What does this tool check?
It checks the TLS connection, validity dates, hostname, issuer, alternative names and certificate fingerprint.
What are SANs?
Subject Alternative Names list the domains and subdomains covered by the same certificate.
Frequently asked questions
Frequently asked questions about SSL certificates
How do I check an SSL certificate?
Enter the domain, keep port 443 and select Check SSL.
When does my SSL certificate expire?
The result shows the expiration date and remaining days.
How do I know if a certificate covers my domain?
The tool compares the hostname with the CN and Subject Alternative Names.
What does self-signed certificate mean?
It means the certificate is signed by itself rather than a recognised trusted authority.
What is a wildcard certificate?
A wildcard such as *.example.com covers one subdomain level, not every nested level.
What are Subject Alternative Names?
They are additional names included in a certificate for other valid domains.
What happens when a certificate expires?
Browsers may show warnings and the connection is no longer considered trusted.
What is the difference between SSL and TLS?
TLS is the modern protocol that replaced SSL, although SSL remains a common term.