SSL Hostname Mismatch Checker
Diagnose 'SSL_ERROR_BAD_CERT_DOMAIN' and similar hostname errors. RunSSLCheck checks the Common Name and Subject Alternative Names to identify exactly which domains the certificate covers.
- 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 Hostname Checker
Check if your domain is covered by its SSL certificate. RunSSLCheck validates the Common Name and all SANs for hostname match. Diagnose hostname mismatch errors instantly.
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