Free SSL Certificate Checker
Instantly check SSL/TLS validity, expiration, issuer, and security grade for any domain. No signup required.
What does an SSL certificate checker verify?
Certificate validity
Whether the certificate is currently valid and trusted by major browsers.
Expiration date
Exactly how many days until the certificate expires — expired certs kill traffic instantly.
Issuer
The Certificate Authority (CA) that issued the certificate — Let's Encrypt, DigiCert, Sectigo, etc.
TLS protocol version
Whether the server is using modern TLS 1.3/1.2 or the deprecated TLS 1.0/1.1.
Cipher suite
The encryption algorithm negotiated between client and server — weak ciphers are a security risk.
Subject Alternative Names
All domains and subdomains covered by the certificate.
Why SSL certificate monitoring matters
An expired SSL certificate takes your site offline for all users — browsers show a hard warning that most users won't bypass. It also disables all form submissions, API calls, and HTTPS traffic. Large companies lose millions per hour of downtime from expired certs.
Best practice is to monitor SSL expiration continuously and receive alerts at 30 days, 14 days, and 7 days before expiry. Xentinel's Protect plan includes automated SSL monitoring with real-time WhatsApp and email alerts.
Popular SSL certificate checks
See live SSL/TLS certificate reports for well-known domains: