TLS Client Hello Mirror

Your browser's TLS Client Hello, reflected as JSON

This test:

• reflects the complete Client Hello message, preserving the order in which TLS parameters and extensions are sent;
• can be used to check for TLS privacy pitfalls (session resumption, TLS fingerprinting, system time exposure);
• supports both HTTP and Gemini;
• is free as in freedom and trivial to self-host.

JSON only, for now, but a UI is on the roadmap.

The API is largely stable - fields may be added, but existing fields will not be modified or removed. IANA-assigned codes for TLS parameters and extensions are documented at:

• TLS parameters
• TLS extensions