SSL Certificate Checker Online
Check SSL/TLS certificate details for any domain: expiry, issuer, SANs, and validity status.
What Is SSL Certificate Checker?
SSL Certificate Checker retrieves and displays SSL/TLS certificate information for any domain using certificate transparency logs. Enter a domain name to instantly see the certificate issuer, validity dates, days until expiry, and all Subject Alternative Names (SANs) covered by the certificate. No browser extension or server access required — data is sourced directly from public CT logs via crt.sh.
How to Use SSL Certificate Checker
- Enter a domain name (e.g.
example.com) in the input field. You can include or omithttps://. - Click Check or press Enter.
- Review the certificate cards showing validity status, issuer, validity period, and SANs.
- Green border = valid, yellow = expiring within 30 days, red = expired.
Features
- Expiry status — color-coded valid / expiring soon / expired badges
- Days remaining — exact count of days until certificate expiry
- SAN display — all hostnames covered by the certificate
- Issuer details — full CA issuer distinguished name
- CT log source — no direct server connection needed, works for any domain
- Recent history — shows up to 5 most recently issued certificates
FAQ
What information does the SSL Certificate Checker show?
The tool shows the certificate common name, Subject Alternative Names (SANs), issuer (CA), validity period (not-before and not-after dates), and the number of days remaining until expiry.
Where does the certificate data come from?
Certificate data is sourced from crt.sh, a public certificate transparency log search engine operated by Sectigo. It indexes certificates from all major CT logs, so results are available without connecting directly to the target server.
Why does the tool show multiple certificates?
Certificate transparency logs record every certificate ever issued for a domain. The tool shows the five most recently issued certificates, which may include the current active certificate, recently renewed certificates, and older expired ones.
What are Subject Alternative Names (SANs)?
SANs are additional hostnames covered by a single certificate. For example, a certificate for example.com may also cover www.example.com and api.example.com. Wildcard SANs like *.example.com cover all direct subdomains.