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RunStack
SSL/TLS Checker

Online SSL/TLS checker

Examples:587: SMTP STARTTLS

Help

How to read the result

Start with the 4-item checklist and “What to do”. The A+/A/B letter is a Runstack TLS Grade guide. “Not tested” ≠ “broken”: some vulns and rare modes are intentionally skipped.

Certificate and name

Trust uses the Node.js store (close to typical servers). Wildcard *.example.com covers www.example.com, but not the apex or a.b.example.com.

Protocols and ciphers

TLS 1.2 + 1.3 with AEAD (AES-GCM / ChaCha20) is enough. Turn off TLS 1.0/1.1. Do not disable TLS 1.2 only to chase A+.

HSTS

Useful for public HTTPS sites on 443. For SMTP/IMAP and non-HTTP ports the item stays “not tested” — that is expected.