Free TLS Protocol Checker
Test which TLS protocol versions a public HTTPS host accepts on port 443 so you can confirm modern TLS support and identify legacy protocol exposure.
Common use cases
- Verify TLS 1.2 or TLS 1.3 support after changing load balancers or CDN settings.
- Find legacy TLS 1.0 or TLS 1.1 support before a compliance review.
- Pair protocol findings with certificate and security header checks during HTTPS hardening.
Frequently asked questions
Which TLS versions are checked?
NerdTools attempts TLS 1.0, TLS 1.1, TLS 1.2, and TLS 1.3 when the local PHP/OpenSSL runtime exposes the matching crypto method.
What port does the TLS checker use?
The TLS checker connects to the public host on port 443.