Offered and negotiated values
ClientHello lists options the client offers. The application's TLS version and cipher describe a completed connection and may differ.
Localtonet tools
TLS fingerprint
See your JA3 and JA4 fingerprints and the TLS options your browser offers.
Your result
Checking
Reading your TLS handshake…
Checking ClientHello metadata at the measurement service.
ClientHelloChecking…
Highest TLS offeredChecking…
Application HTTPChecking…
TLS & HTTP request data
JA4 · TLS ClientHello
Waiting for the test…JA3 · MD5 of ClientHello parameters
Waiting for the test…Application request signature
Waiting for the test…Run the check to see the measured values.
Fingerprints describe the client that connects to the measurement service. A proxy that terminates TLS changes the result.
How it works Guidance & troubleshooting
What these fingerprints describe
The measurement service reads the first TLS ClientHello before completing normal HTTPS verification. JA3 and JA4 summarize its offered versions, cipher suites and extensions. GREASE values are excluded.
Compare fingerprints before and after a browser or proxy change. The separate app- signature summarizes details visible to the website application. For properties exposed by page scripts, use the browser fingerprint test.
The hosting path matters
A TLS-terminating proxy becomes the client observed by the measurement service. A tunnel that passes TLS through preserves the browser handshake.
Comparing fingerprints
Fingerprints can be shared by many browsers and may change after updates. They do not identify a person.
Capture limits
This measurement covers TLS over TCP. QUIC, DTLS and an encrypted inner ClientHello are outside its capture scope.
Common questions
Are JA3 and JA4 measured directly?
Yes, when the measurement service returns a captured ClientHello. If capture is unavailable, no JA3 or JA4 value is claimed.
Why is the TLS version unavailable?
The TLS connection may terminate at a reverse proxy or CDN that does not forward the negotiated details to the application.
Why does the signature change?
HTTP negotiation, headers, browser updates and intermediary behavior can all change the application-visible request.
