SSL / TLS
SSL Certificate Checker
Check any domain's SSL/TLS certificate — verify the expiry date, issuer, SANs, wildcard coverage, and exactly how many days remain.
Overview
What is an SSL/TLS certificate?
SSL and TLS are security protocols that encrypt data between a visitor's browser and a website. TLS is the newer protocol, but many people still call the certificates "SSL certificates."
When a website has a valid certificate installed, it can serve traffic over HTTPS. This protects data in transit from interception or tampering and is a standard part of modern website security.
Why SSL matters for trust, security, and search
A certificate problem can hurt trust, cause warnings, and interrupt the user experience.
Protecting data in transit
A valid certificate is a standard part of protecting login data, contact forms, checkout details, and other information sent between users and your website.
Search and user experience
HTTPS is a known ranking signal, and certificate problems can reduce trust, disrupt conversions, and trigger prominent browser warnings that discourage visits.
Understanding certificate details
Certificate authority
The issuer is the certificate authority that signed the certificate and helps establish browser trust.
Subject alternative names
SANs are additional hostnames covered by the same certificate, such as multiple subdomains or related domains.
Wildcard coverage
Wildcard certificates can cover many first-level subdomains under the same base domain, depending on the certificate scope.
Did your certificate expire?
If your site shows a certificate warning, renew and reinstall a valid certificate as soon as possible. Free certificate authorities such as Let's Encrypt make it possible to automate renewal for many websites.
Answers
Frequently asked questions
How do I check if my SSL certificate is valid?
Enter your domain into our SSL certificate checker. The tool connects to the server, reads the certificate, and shows validity dates, issuer, SANs, wildcard coverage, and days remaining.
What happens when an SSL certificate expires?
When a certificate expires, browsers display strong security warnings and many users will avoid proceeding to the site until the certificate is renewed.
What is a SAN in an SSL certificate?
A Subject Alternative Name, or SAN, is an additional hostname covered by the certificate. It allows one certificate to secure multiple hostnames or subdomains.
Why does my website show Not Secure?
This can happen when a certificate has expired, does not match the hostname, is self-signed, or when a secure page loads insecure content.
Can I use a free SSL certificate?
Yes. Free certificate authorities such as Let's Encrypt provide widely trusted certificates suitable for many websites.
Full picture
Check the whole domain's health
Combine SSL with DNS, blacklist, and email checks in one report.