SSL Certificate Checker

What Is an SSL/TLS Certificate?

An SSL (Secure Sockets Layer) certificate — now more accurately called a TLS (Transport Layer Security) certificate — is a digital document that authenticates a website's identity and enables encrypted communication between a web browser and a web server. When you see the padlock icon in your browser's address bar, it means the site has a valid SSL/TLS certificate and your connection is encrypted using HTTPS.

Why Check SSL Certificates?

Regularly checking your SSL certificates is essential for maintaining website security and uptime. An expired certificate will trigger browser warnings that scare visitors away and can break API integrations, payment processing, and other critical services. This tool lets you verify that a certificate is properly installed, check its expiration date, inspect the certificate chain, and confirm that it covers the correct domain names (including subdomains via wildcard or Subject Alternative Names).

Understanding Certificate Chains

SSL certificates rely on a chain of trust. Your server's certificate is signed by an intermediate Certificate Authority (CA), which is in turn signed by a trusted root CA. All links in this chain must be valid for a browser to trust the connection. A broken or incomplete chain is one of the most common SSL configuration errors — this tool shows you every certificate in the chain so you can quickly identify issues.

Expiry Monitoring

Most SSL certificates are valid for one year. With services like Let's Encrypt issuing 90-day certificates, keeping track of renewal dates is more important than ever. Use this tool to check how many days remain before your certificate expires. We color-code the result: green means more than 30 days remaining, amber indicates 7 to 30 days, and red warns of fewer than 7 days or an already-expired certificate. Bookmark this page and check your domains regularly to avoid unexpected outages.