SSL Certificate Checker
Test a site's SSL/TLS certificate in seconds: see when it expires, whether browsers trust it, if it matches the domain, and which TLS versions the server still allows.
Checked live from our server — no signup Free, no limits
How to use the SSL Checker
- Enter a domain name such as example.com (a pasted URL works too).
- Choose port 443 (standard HTTPS) or 8443, and whether to test TLS versions.
- Click Check SSL.
- Read the verdict and expiry countdown, then review the certificate details, chain and SAN list.
Frequently asked questions
How do I check when an SSL certificate expires?
Enter the domain above — the countdown shows exactly how many days are left and the expiry date. Certificates from Let's Encrypt last 90 days and are normally renewed automatically about 30 days before expiry, so a count under 30 days often means renewal is failing.
What happens when an SSL certificate expires?
Browsers show a full-page "Your connection is not private" warning, most visitors leave, and APIs or apps that connect to the site start failing. Renewing and installing a new certificate fixes it immediately.
What does "certificate name mismatch" mean?
The certificate doesn't list the domain you visited in its Subject Alternative Names. Common causes are a missing www or non-www name, a wildcard that doesn't cover a deeper subdomain, or the server sending the default certificate for another site.
Why is my certificate chain incomplete or untrusted?
Your server must send its intermediate certificate(s) along with the site certificate. If it only sends the leaf, some browsers and most apps can't build a path to a trusted root. Install the full chain (often called fullchain.pem) from your certificate authority.
Should TLS 1.0 and 1.1 be disabled?
Yes. Both were formally deprecated in 2021 (RFC 8996) and all major browsers have dropped them. Servers should offer TLS 1.2 and TLS 1.3 only.
Is it safe to check any site?
Yes. We only open a normal TLS connection like a browser does and read the public certificate the server presents — nothing is changed or stored.