SSL Certificate Checker
Check SSL/TLS certificate validity, expiration date, and certificate chain details online
Enter a domain name and click "Check" to view SSL certificate info
What is SSL Certificate Checker?
An SSL certificate checker verifies whether a website's SSL/TLS certificate is valid, about to expire, and properly matched to the domain. SSL certificates are the foundation of HTTPS encrypted communication — ensuring their validity protects website security and user data privacy. With this tool, you can quickly understand a target website's certificate status, encryption protocol version, certificate chain details, and more.
How to Use
- Enter the domain name you want to check (e.g. google.com)
- The default port is 443. Change it if needed for special configurations
- Click the "Check" button or press Enter to start the check
- View certificate validity, expiration date, TLS protocol version, and more
- Expand the certificate chain to see detailed info for each certificate including issuer, signature algorithm, SANs, etc.
FAQ
Q: What happens when an SSL certificate expires?
A: When an SSL certificate expires, browsers will display security warnings and users may be unable to access the website normally. It's recommended to renew certificates before they expire — this tool specifically highlights certificates expiring within 30 days.
Q: What is a certificate chain?
A: A certificate chain is the trust path from the leaf certificate (website certificate) to the root certificate (CA authority). Browsers verify the certificate chain to confirm the website certificate's trustworthiness. A complete certificate chain helps ensure all clients can verify it correctly.
Q: What does domain mismatch mean?
A: Domain mismatch means the domain in the certificate (Subject or SAN) doesn't match the domain you're accessing. This could be due to certificate misconfiguration or using the wrong domain. It commonly occurs when accessing via IP address or when the certificate doesn't cover subdomains.
Q: What is a TLS protocol version?
A: TLS (Transport Layer Security) is the successor to SSL, used to encrypt network communication. TLS 1.2 or TLS 1.3 is currently recommended — older versions (like TLS 1.0, 1.1) are deprecated and have security risks.