SSL Certificate Checker
Verify any domain's SSL/TLS certificate — expiry, issuer, SANs, key type, and validity
Frequently Asked Questions
example.com might also cover www.example.com, mail.example.com, and *.example.com (wildcard). Modern browsers require SANs — the Common Name (CN) field alone is no longer accepted as valid.OV (Organization Validated): Verifies the domain and the organization behind it. Better for businesses.
EV (Extended Validation): Most rigorous — verifies legal identity of the organization. Previously showed a green bar in browsers; now shown in cert details.
*.example.com covers www.example.com, api.example.com, mail.example.com, etc., but not sub.api.example.com (two levels deep). Wildcard certs save money when you need to secure many subdomains.certbot renew --dry-run to verify your auto-renewal is configured correctly. For paid certificates from CAs like DigiCert, Sectigo, or Comodo, log in to your account and generate a new CSR (Certificate Signing Request) before expiry. Monitor expiry dates proactively — use this tool or set a calendar reminder at 30 and 7 days before expiry. Never let a certificate expire in production.*.example.com) covers all subdomains at one level — www.example.com, api.example.com, mail.example.com — but not the root domain itself or deeper subdomains like dev.api.example.com. A SAN (Subject Alternative Names) multi-domain certificate explicitly lists multiple different domains in the certificate, such as example.com, example.net, and otherdomain.org. Wildcards are ideal when you have many subdomains under one domain; SANs are ideal when you manage multiple distinct domains. Both types can be combined (a wildcard SAN cert can cover *.example.com and *.otherdomain.org).ssl_certificate to the combined file. For Apache, use SSLCertificateChainFile or include intermediates in the cert file. Use the SSL Labs test to verify chain completeness.About This SSL Checker
This free SSL Certificate Checker connects directly to the target server on port 443 and retrieves the SSL/TLS certificate in real time. It shows the certificate's common name, organization, issuer (Certificate Authority), validity dates, days remaining, subject alternative names (SANs), key type and size, and signature algorithm. The tool checks whether the certificate chain validates correctly against trusted root CAs.
Common Certificate Authorities
| CA | Type | Notes |
|---|---|---|
| Let's Encrypt | DV | Free, 90-day, auto-renew |
| DigiCert | DV/OV/EV | Premium, widely trusted |
| Sectigo | DV/OV/EV | Formerly Comodo |
| GlobalSign | DV/OV/EV | Enterprise focus |
| ZeroSSL | DV | Free 90-day certs |
| Amazon ACM | DV | Free for AWS services |
SSL Certificate Status Guide
| Status | Meaning |
|---|---|
| Valid | Certificate is current and trusted |
| Expiring Soon | Expires within 30 days |
| Expired | Certificate has expired |
| Untrusted | Chain not trusted by browsers |
| Self-Signed | Not issued by a public CA |
Standards & References
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