TLS fingerprint checker
Your JA3 and JA4 — the fingerprint of the TLS ClientHello your software sends. Read live below from the probe, which peeks the handshake of your connection: this is how this client looks on the wire, and whether the corpus has seen it before.
Your browser
From your own client
The probe fingerprints whatever connects and returns JSON — so curl, Python, Go, a browser and your own app each get a different JA4. No key, no rate limit, CORS-open.
curl https://probe.tls-reputation.com:8443/Example output
curl isn’t a recognised browser, so known is null and its handshake is deterministic (stability: fixed). A real Chrome or Firefox returns its name and a completely different JA4.
{
"ja4": "t13d4907h2_0d8feac7bc37_7395dae3b2f3",
"ja3": "375c6162a492dfbf2795909110ce8424",
"tls_version": "TLS 1.3",
"alpn": ["h2", "http/1.1"],
"known": null,
"observed": true,
"reputation": {
"observations": 26,
"unique_snis": 10,
"spread": 0.855,
"stability": { "class": "fixed" }
}
}What is a TLS fingerprint?
What is a TLS fingerprint?
Every TLS connection opens with a ClientHello that offers a set of versions, cipher suites, extensions and elliptic curves. Their exact selection and order is characteristic of the client software, hashed into a JA3 or JA4 fingerprint. It identifies software, not people — two people on the same Chrome build share a fingerprint.
JA3 or JA4 — what's the difference?
JA3 (Salesforce) is the older scheme: an MD5 hash of the ClientHello. JA4 (FoxIO) is the current one: human-readable and robust to the extension shuffling modern browsers do to resist fingerprinting. This checker shows both.
How do I check my TLS fingerprint?
Open this page and it reads your browser's fingerprint live from the probe. To fingerprint any other client, request https://probe.tls-reputation.com:8443/ with curl, Python, Go or Node — it returns that client's JA3/JA4 as JSON, no key or rate limit.