SSL Certificate Checker
Check a domain's SSL certificate details and expiry.
This is one of three tools on this site that need a server-side connection: checking a live domain's certificate requires an actual TLS handshake, which a browser can't make directly to an arbitrary domain. The domain you enter is used only to make that one connection and is not logged or stored.
- Real TLS handshake to the domain, not a cached or third-party database lookup.
- Clear expired / expiring-soon / valid status, colour-coded.
- Shows issuer, subject, validity dates, serial number, fingerprint and alternative names.
Overview
Connects to a domain on port 443 and reports its SSL/TLS certificate — issuer, subject, validity dates, and an expiry warning if it's close to running out.
How to use it
- 1Enter a domain name.
- 2Click Check.
- 3Review the certificate's status and details.
Frequently asked questions
What people use it for
Confirm a certificate renewed correctlyCheck the new validity dates after rotating or renewing a certificate.
Catch an expiring certificate before it lapsesA lapsed certificate breaks HTTPS for every visitor — check ahead of a deadline.
Verify which CA issued a certificateConfirm the issuer matches what you expect, e.g. after a certificate authority migration.
Check a certificate's alternative namesConfirm every subdomain you need is actually covered.
Related tools
All security toolsSecurity Headers CheckerCheck a live site's security-related HTTP headers, with a letter grade.CSP GeneratorBuild a Content-Security-Policy header, including frame-ancestors and a report-only rollout mode.Password Strength CheckerCheck a password's strength and estimated crack time.HMAC GeneratorGenerate an HMAC signature for a message with a secret key.
Ready to use SSL Certificate Checker?
SSL Certificate Checker