🔒 SSL/TLS Checker

What this tool checks

• Certificate details - subject, issuer, validity period, key type & size, signature algorithm
• TLS protocol support - TLS 1.2 and 1.3 probed independently; deprecated versions flagged
• Cipher suite - active cipher name, protocol, and key strength
• HSTS - max-age value, includeSubDomains, preload flag
• HTTP/2 - ALPN negotiation check
• Certificate Transparency - SCT count from certificate extension
• Extended Validation (EV) - detects EV OIDs in certificate policies
• Fingerprints - SHA-256 and SHA-1 certificate fingerprints
• HTTPS redirect - whether HTTP:80 redirects to HTTPS

Grading scale

• A+ - Excellent: HSTS preload, long max-age, TLS 1.3, strong key, CT
• A - Good: TLS 1.2+, valid cert, HSTS enabled, strong cipher
• A− - Good with minor recommendations
• B - Moderate: some security enhancements recommended
• C / D - Significant issues: weak keys, missing HSTS, TLS 1.1
• F - Fail: invalid or expired certificate, critical vulnerability