How do I check if an SSL certificate is valid?

Enter the domain into an SSL certificate checker. It connects to the server and retrieves the certificate details including expiry date, issuer, and trust chain status.

What happens when an SSL certificate expires?

When an SSL certificate expires, browsers show a security warning blocking access. Certificates should be renewed before expiry — Let's Encrypt certificates last 90 days, commercial ones typically 1 year.

SSL / TLS

SSL Certificate Checker

Check any site's SSL certificate — expiry, issuer, SANs, and chain validity.

Try:

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SSL Certificate Checker — What to Look For

An SSL/TLS certificate establishes an encrypted connection between a browser and web server. Checking certificates regularly prevents unexpected downtime from expiry.

Certificate Expiry

Let's Encrypt certificates last 90 days; commercial certificates typically 1 year. Set up auto-renewal or reminders at least 30 days before expiry.

Subject Alternative Names (SANs)

SANs list all domains covered by the certificate. A wildcard (*.example.com) covers all subdomains. A multi-domain cert explicitly lists each covered domain.

Certificate Chain

A valid chain connects your certificate through intermediates to a trusted root CA. A broken chain causes browser warnings even if the leaf certificate is valid.