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SSL Checker — Verify Your SSL/TLS Certificate Online | TestURL.live
SSL

SSL Checker — Verify Your Certificate In Seconds

Check any HTTPS host's TLS certificate: issuer, expiry, SAN list, signature algorithm, hostname match, and chain validity. Catch expiring certs before they bite.

Migrating to a new server?

Test the migration with a preview URL before DNS — confirm AutoSSL/Let's Encrypt has issued the new cert.

Test Your Migration →

What This SSL Checker Verifies

When To Use It

Pre-migration check

You're moving to a new host. Did AutoSSL / Let's Encrypt issue a valid cert on the new IP?

Expiry monitoring

Set a reminder when the days-to-expiry drops below 30. Catch certs before they break payments.

Mixed-content debugging

If a subdomain throws cert errors, check it specifically. Wildcards don't cover apex; multi-domain SANs need every name listed.

API endpoints

Your customers rely on api.yoursite.com. Check the cert is valid even when the marketing site looks fine.

SSL Checker FAQ

What does an SSL checker do?

It opens an HTTPS connection, performs the TLS handshake, captures the certificate the server presents, and reports the issuer, validity window, SANs, signature algorithm, and whether the chain is trusted.

Why is my certificate showing 'untrusted'?

Most often: missing intermediate certificates in the chain (the server only sent the leaf), or a self-signed cert. The "chain" section of the result shows what the server sent — compare against your CA's recommended bundle.

Can I check a cert on a non-standard port?

Yes. Enter host:port (e.g. example.com:8443). The checker connects to that port.

Why does the SAN list matter?

Modern browsers ignore the certificate's CN and rely entirely on the SAN list. If your visitor uses www.example.com but the cert only lists example.com in SANs, they'll see an error — even though the CN says www.example.com.

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