SSL Certificate Checker — Free Online SSL/TLS Certificate Validator
Check any domain's SSL certificate validity, expiry date, issuer, SANs, and TLS protocol version in real time.
Frequently Asked Questions
SSL/TLS Certificate Validation
SSL/TLS certificates are the foundation of HTTPS security. They authenticate your server identity and encrypt traffic between the server and browser. An expired, misconfigured, or untrusted certificate immediately breaks HTTPS and displays browser security warnings to all visitors.
This SSL checker performs a live TLS handshake with the target server and extracts the certificate details: expiry date, issuer chain, subject alternative names, serial number, fingerprint, and TLS protocol/cipher information. This is the same information a browser inspects when establishing a secure connection.
Regular SSL monitoring is essential for production infrastructure. Certificate expiry is a common cause of outages — even experienced teams let certificates lapse. Set up automated monitoring alerts at 60, 30, and 14 days before expiry to avoid service disruptions.