Free SSL Certificate Checker

Use the free SSL checker tool to check SSL certificate details for any domain or hostname. Enter a domain above and the tool will return the certificate details.

Understanding SSL certificate fields

An SSL (or TLS) certificate is a digital document issued by a Certificate Authority (CA) that binds a public key to a domain name, enabling HTTPS encryption and allowing browsers to verify the identity of a web server. Here are some of the most important fields the SSL Checker returns:

• Issuer Organization: The organization behind the issuing CA (e.g. DigiCert or Sectigo).
• Subject (CN): The common name the certificate was issued to, typically the domain name.
• Subject Alternative Names: Additional domains or subdomains covered by the same certificate.
• Issued Date / Expiry Date: The validity window for the certificate. After the expiry date, browsers will block or warn visitors about your site.
• Currently Valid: Whether the certificate is trusted. Revocation or domain mismatch can invalidate a certificate before it expires.

How to check SSL certificate expiration date

Enter the domain above and the tool will show the exact expiry date and days remaining. A certificate that expires without being renewed will cause browser security warnings and break HTTPS for your visitors.

To get alerts before that happens, SSL certificate monitoring in Testomato checks your certificates automatically and notifies you in advance. See how to configure SSL expiry alerts in Testomato.