SSL Certificate Not Trusted Checker
Diagnose why browsers show 'Your connection is not private' or 'Certificate not trusted'. RunSSLCheck checks trust, the chain, and the root CA to identify the exact cause.
- Live TLS handshake
- Trust & chain validation
- Expiry countdown
- TLS 1.0–1.3 detection
How the SSL checker works
Check any SSL certificate online in three simple steps — no signup, no downloads.
1. Enter a hostname
Type any domain or subdomain — for example example.com or mail.example.com. You can paste a full URL; we'll clean it up automatically. Add :port for non-standard ports.
2. We connect live
RunSSLCheck opens a real TLS connection to the server and inspects the exact certificate it presents — no cached data and no third-party API.
3. Read your results
See trust status, hostname match, expiry countdown, the full certificate chain, key strength, and which TLS versions are enabled.
Everything you need to check SSL certificates
A complete SSL certificate checker that goes beyond a simple pass or fail.
Trust & installation check
Confirms the certificate is valid, trusted by major browsers, and that all intermediate certificates are correctly installed.
SSL certificate expiry check
Shows the exact validity window and a clear countdown of days remaining so you can renew before visitors ever see a warning.
Full certificate chain
Visualizes the path from your server certificate up to the trusted root CA, with downloadable PEM for every certificate.
Key & protocol analysis
Reports key type and size, signature algorithm, and detects every supported TLS version from 1.0 to 1.3.
Frequently asked questions
Common questions about this SSL checker tool.
Related SSL checkers
More tools to check every aspect of your SSL certificate.
SSL Trust Checker
Check if your SSL certificate is trusted by major browsers. RunSSLCheck validates against the system trust store via a live TLS handshake. Free, instant, no signup.
Check nowSSL Chain Incomplete Checker
Check for incomplete SSL certificate chains and missing intermediate certificates. RunSSLCheck shows exactly where the chain breaks. Free, live chain checker.
Check nowSelf-Signed Certificate Checker
Detect self-signed SSL certificates that cause browser trust errors. RunSSLCheck identifies when a certificate is signed by itself rather than a trusted CA. Free, instant.
Check now