CERTINITE · FREE SSL TOOLS

SSL Certificate & Expiry Checker

Check a public website’s SSL certificate, expiry date, hostname coverage and trust chain. See days remaining and practical fixes. No signup required.

  • No signup required
  • Full results, always free
  • Built for IT & DevOps

Use this tool free, without an account

Enable JavaScript to use the interactive tool. Instructions and troubleshooting guidance are available below.

How it works

Enter a domain without a URL or port. Certinite resolves its public DNS and opens an SNI-aware TLS connection on port 443. The report describes the certificate served to our checker, with a UTC check time.

What does this tool check?

  • Validity dates and days until expiration
  • Issuer, subject, SANs, serial number and SHA-256 fingerprint
  • Hostname matching, self-signed signatures and operating system chain trust
  • Public key strength and the negotiated TLS protocol and cipher

Common issues & how to fix them

Expired or expiring certificate

Renew the certificate, install the new full chain on every relevant TLS endpoint, and reload the service. A CDN or load balancer may terminate TLS separately from your origin.

Hostname mismatch

Make sure the certificate SAN includes the exact hostname and the correct certificate is selected by the server’s SNI configuration. A wildcard covers one label, not every nested subdomain.

Unable to connect

Check public A/AAAA records, port 443 and firewall rules. A failed connection cannot establish whether a certificate is installed.

Frequently asked questions

What do Healthy, Warning, Critical and Expired mean?

Expired means the leaf certificate’s expiry time has passed. Critical means a hostname, validity, self-signed or chain validation problem was found. Warning means expiry is within 30 days or weak certificate cryptography was detected. Healthy means these specific checks found no issue; it is not a complete security audit.

Is this continuous SSL monitoring?

No. This is an on-demand snapshot of one reachable endpoint. Results may be cached for three minutes. Certinite’s supported automation workflows can handle ongoing certificate renewal and deployment.

Does a healthy result prove every browser will trust my site?

No. Trust stores, network paths and cached intermediates differ. Revocation, Certificate Transparency and every supported TLS version are outside this check.

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