Free SSL Certificate Checker
Check any website's SSL certificate in seconds: who issued it, when it expires, which names it covers and whether browsers will trust it.
SSL Certificate Checker: Check any website's SSL certificate in seconds: who issued it, when it expires, which names it covers and whether browsers will trust it. It is free, needs no sign-up and runs in your browser. How to use it: 1) enter the domain name you want to check; 2) click Check SSL certificate and wait a few seconds; 3) review the days left, the checks and the list of covered domains. Our server opens a secure connection to the domain on port 443, just like a browser, and reads the certificate the site sends. It then shows the issuer, the valid from and expiry dates, the number of days left and every domain name listed on the certificate.
How the SSL certificate checker works
Our server opens a secure connection to the domain on port 443, just like a browser, and reads the certificate the site sends. It then shows the issuer, the valid from and expiry dates, the number of days left and every domain name listed on the certificate.
What is checked
- Expiry: green when more than 30 days are left, amber from 8 to 30 days and red at 7 days or less or once expired.
- Hostname match: the domain you entered must appear in the certificate names, including wildcard names such as *.example.com.
- Self-signed: certificates that sign themselves are not trusted by browsers.
- www and non-www: whether both versions of the domain are covered.
- Validity period: public certificates longer than 398 days are rejected by browsers.
Why it matters
An expired or mismatched certificate shows a full page security warning that stops most visitors and buyers. Free certificates from Let’s Encrypt last 90 days, so auto renewal must work every time.
Limitations
The tool reads the certificate only. It does not test the full certificate chain, TLS protocol versions, cipher strength or mixed content inside your pages. Sites behind a CDN show the CDN certificate, not the one on your origin server. This check needs an internet connection.
SSL Certificate Checker FAQs
How do I check when my SSL certificate expires?
Enter your domain and click Check SSL certificate. The tool shows the exact expiry date and the number of days left, with a colour badge. Green means more than 30 days, amber means renew soon and red means it expires within a week or has already expired.
Why does my site show a certificate name mismatch?
A mismatch means the certificate does not list the exact domain visitors use. A common cause is a certificate for example.com that does not include www.example.com, or the reverse. Reissue the certificate with both names, or use a wildcard certificate that covers your subdomains.
Are free SSL certificates safe to use?
Yes. Free certificates from Let’s Encrypt or Cloudflare give the same encryption as paid ones and are trusted by all major browsers. Paid certificates can add business validation or a warranty. Free certificates last 90 days, so make sure automatic renewal is set up on your host.
What happens when an SSL certificate expires?
Browsers show a full page warning saying the connection is not private, and most visitors leave. Forms and checkouts stop working for many users, and Google may show the warning page in tests. Renew before expiry and check that your host renews certificates automatically.
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