SSL Certificate Check Online - Validity & Certificate Chain
Validity / Certificate chain / Cipher / SAN
About SSL Certificates
SSL/TLS certificates provide HTTPS encryption; make sure the certificate subject matches the domain, sufficient validity remains and the certificate chain is complete. This tool inspects the certificate validity, issuer, certificate chain, cipher, signature algorithm, key size and SANs (Subject Alternative Names). When troubleshooting HTTPS, first confirm resolution with DNS Lookup, then check the endpoint response with HTTP Test.
Typical Scenarios for SSL Certificate Checks
Renewal reminders: periodically check remaining days to avoid outages from expiration. Configuration verification: after replacing a certificate, confirm the chain is complete and the SANs cover all subdomains. Security audits: check whether cipher strength and key size meet standards (RSA 2048+ or ECDSA recommended).
FAQ
What should I do if my SSL certificate has expired?
Once expired, browsers block access and warn that the site is "not secure". Re-apply or renew the certificate with the original CA, download the new certificate, replace the old files on the server and restart the web service. You can use this tool to verify the new certificate is active.
What is the difference between DV, OV and EV certificates?
DV (Domain Validation) only verifies domain ownership and issues fastest; OV (Organization Validation) additionally verifies the company identity and shows the organization name in the certificate; EV (Extended Validation) has the strictest review and shows a green company name in the address bar. Most websites only need DV for HTTPS encryption.
What is a certificate chain and why must it be complete?
A certificate chain is the trust path from the server certificate → intermediate CA → root CA. If the intermediate certificate is missing, some browsers consider the certificate untrusted. A complete chain ensures all clients can correctly validate the certificate.
What is SAN?
SAN (Subject Alternative Name) lets one certificate protect multiple domains. For example, a single certificate can cover both example.com and www.example.com, avoiding a separate application for each subdomain.