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SSL Certificate Checker

Check an SSL certificate's hostname, expiry date, issuer, and trust chain for a public HTTPS domain.

Guide

Interactive workspace

No account required
Check an SSL certificate

Connects to the domain on port 443 and reads the certificate the server presents: expiry, issuer, covered hostnames, and chain of trust.

Enter a domain to see its certificate expiry date, issuer, covered hostnames, and chain.

How to use it

  1. Enter the hostname you want to inspect, without a page path.
  2. Run the TLS check and read the validity and days-to-expiry status.
  3. Confirm the certificate covers the hostname and inspect the issuer and chain.
  4. Repeat for www and any other subdomains your site serves.
What is SSL Checker?

Check an SSL certificate's expiry date, issuer, covered hostnames, chain of trust, and TLS version for any domain.

How it works

SiteIndex opens a TLS connection to the domain on port 443 using SNI, reads the certificate chain the server presents, and verifies it against trusted root authorities. It reports expiry and days remaining, the issuer, subject alternative names, whether the hostname matches, the negotiated TLS version and cipher, and whether HTTP/2 is offered via ALPN.

Common uses
  • Check when a certificate expires and confirm auto-renewal worked.
  • Diagnose browser security warnings caused by a hostname mismatch or missing intermediate certificate.
  • Confirm a new certificate covers every subdomain you need (www, api, etc.).
Limitations
  • Results depend on the browser, network, input, and external service involved.
  • This tool is informational and does not replace specialist diagnostics or professional advice.
Frequently asked questions
How do I check a website's SSL certificate?
Enter the domain and run the check. SiteIndex shows whether the certificate is valid, when it expires, who issued it, which hostnames it covers, and whether the full chain is trusted.
Why does my certificate say the chain is not trusted?
Most often the server is not sending the intermediate certificate. Install the full chain (fullchain.pem) provided by your certificate authority and re-check.
Is SSL the same as TLS?
TLS is the modern successor to SSL. People still say "SSL certificate", but today's HTTPS connections use TLS 1.2 or TLS 1.3.

Learn more

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